Like the bowels of heaven opening is how Lovefoxxx, the doe-eyed singer of CSS, describes the weather at last year’s Glastonbury (we’re paraphrasing). “Or like Hurricane Katrina had hit and instead of everyone getting depressed they were partying,” adds the befringed guitarist Carol Parra.

This is what the Brazilian quintet are like – a mad mix of high-octane fun and bad taste jokes. Remember those early Spice Girls interviews when members finished off one another’s sentences? They are like that, with a wry touch of added sitcom.

Sitting backstage before their headline slot on Glastonbury’s Park Stage, the band are relaxed; cracking jokes about James Blunt and basking in a rare day of Pilton sun. The weather was, of course, very different when they played in 2007. Nevertheless, CSS’s mid-afternoon set then was a ray of light amid the grimness.

Remembered largely for Lovefoxxx’s rainbow sequined catsuit, the highly charged new wave of Off the Hook and slinky electro of indie-disco staple Let’s Make Love and Listen to Death from Above had many forgetting about their sodden tents.

It was the pinnacle of their amazing year. With an effortless and non-ironic joie de vivre, CSS were embraced by the UK for their camp punk attitude. Their self-titled debut’s mix of fuzzy, lo-fi electro pop ranked among the best of 2006. It was also clear from their live shows that this was the kind of loveable, scrappy, surreal gang that everyone wanted to be part of.

Their reappearance this year may have been overshadowed by Jay-Z’s Noel Gallagher tribute, but it was significant to CSS for entirely different reasons. Behind the camp glamour of catsuit numero deux (black with large blue flowers) and the deceptive jaunt of the new single Left Behind lay a tale of adversity that almost cost the band their career. The lyrics (“I’m gonna jump on to the table and dance my ass off till I die/And then I’ll hopefully forget you and quit those nightmares I’ve been having”) were penned when the band were at their wits’ end, desperately trying to keep it together after a financial meltdown and a personal bust-up.

CSS began in 2003 when six friends (guitarist Luiza Sa, drummer/ guitarist Adriano Cintra, bassist Ira Trevisan, keyboardist/ guitarist Ana Rezende, drummer/guitarist Carol Parra and singer Luisa Matsushita aka Lovefoxxx) bonded over a shared love of US celebrities, avant-garde art and female singers.

Naming themselves after a Beyoncé quote (she said she was “tired of being sexy”, in Portuguese “Cansei de Ser Sexy”), the band started gigging in their native São Paulo. And songs such as I Want to Be Your J-Lo – which combined a skeletal reinterpretation of Eighties pop with funny, knowing lyrics – attracted a local following.

The band were part of a wave of unconventional bands; at a time when Baile funk was coming out of the streets, CSS were also redefining what it meant to be a Brazilian band. “People have an image of what a Brazilian band should sound like. It’s very weird for someone who’s not Brazilian to understand what made us, us,” Parra says. “The Brazilian band that I liked the most, As Mercenarias, weren’t at all like traditional Brazilian music. They sounded like an all-girl Gang of Four,” Cintra adds.

It didn’t take long for the band’s popularity to spread. They released their debut independently in 2006. A deal with the US label Sub Pop followed, by which time they were touring nonstop. They went from co-headlining NME’s New Rave tour with Klaxons (to whose guitarist, Simon Taylor-Davis, Lovefoxxx is engaged) to playing virtually every big UK festival in 2007. But something was awry.

“It was August of last year,” Cintra says. “And after a show our agent came to us to tell us that he’d just received our cheque for playing and I thought, ‘Man, I’m rich!’ but the money never came.” Their manager Eduardo had been overspending.

“My place in Brazil had the electricity cut off because I couldn’t pay the bill,” Cintra continues. “Whereas Eduardo always had really expensive clothes, ate in really good restaurants and had an apartment in Paris.”

A confrontation followed and Eduardo was fired. The fall-out was significant. Not only was the band in debt, Eduardo’s girlfriend was bassist Ira Trevisan. She left the band in April, in a statement saying she wanted to focus “on fashion and other projects”. The suspicion, however, was that she was simply too embarrassed to stay.

There is an uneasy silence. “I couldn’t tell, but she was the manager’s girlfriend,” Cintra says. Parra believes her heart was never in it. “Even in the beginning she was the one who wasn’t sure about being in the band,” she says.

The scars are still evident. A video of the band hitting a Guy Fawkes-like effigy of Eduardo with sticks appeared on their website a few months ago. Though with their sunny demeanour today at Glastonbury, it’s hard to imagine the tensions that were pulling at the band at the time.

Salvation came from an unlikely source – Gwen Stefani. A support slot on her autumn tour helped them to refocus. “It was a time we really needed to be together,” Parra says. It was during this tour that Left Behind was penned. “It was written about Eduardo,” Cintra says. “We were DJing in this club in Helsinki. People were dancing on tables, tearing lampshades off lights, wearing them as hats. And it was the first time in ages that I felt good after all that horrible s*** that had happened.”

The band soon acquired a new manager and what they thought would tear them apart did the opposite. “Those experiences brought us closer,” Lovefoxxx says. “Bobby Gillespie [of Primal Scream] told me we’d officially become members of The Rock’n’Roll Club because we got stiffed by our manager.”

The reenergised band decamped to São Paulo to record their second album. Informed by the rockier sound they had developed as a result of playing live so much, Donkey is harder than their debut. The heart of the disc is fused with songs (Give Up and How I Became Paranoid) that reflect their emotional rollercoaster year. A long tour follows to promote Donkey, which the band can look forward to.

With the money finally rolling in, the band members have realised their lifelong dreams of moving to London. Reflecting on how they’ve grown, Lovefoxxx says: “I feel like last year we were like the team in Cool Runnings,” a reference to the film about the Jamaican bobsled team. “But now it’s like we’ve moved to where it’s cold so we know what we’re doing now.”

Donkey is out on July 21 on Sub Pop

Explore Music

• CD Reviews

• Live Reviews

• Classical

Editor's choice

• The 100 Best Films of the Decade
• 70 facts you didn't know about Marvel
• The 50 Biggest Movies Of 2010