Three members of Bucks Fizz say they are "bitterly disappointed" at a court ruling preventing them from using the band's name.
Bobby G, whose wife Heidi Manton owns the trademark for the name, took legal action to stop Cheryl Baker, Mike Nolan and Jay Aston performing as The Original Bucks Fizz.
They then challenged his use of the name Bucks Fizz, claiming it was misleading to fans and attempted to revoke the trademark.
The trio's lawyer, Dean Dunham, told Sky News Online they are "bitterly disappointed" and "it is totally the wrong decision."
He added: "We are going to appeal to the high court. I am confident we will win the case."
In court papers made official this week, it emerged that Bobby G, real name Robert Gubby, can continue using the name, and the other three should stop calling themselves The Original Bucks Fizz.
Baker, Nolan, Aston and Gubby shot to fame when Bucks Fizz won the Eurovision Song Contest with Making Your Mind Up in 1981.
Mr Dunham said: "They never wanted it to come to this, Bobby G was the aggressor. There is overwhelming evidence to show the public are being misled."
"Bobby G's group even had posters showing the winners of Eurovision in their advertisements."
During a hearing at the Intellectual Property Office on July 15, Mr Dunham argued that Bucks Fizz fans had been left "disappointed" to discover they had booked tickets for a band featuring only one member of the original line-up.
Cheryl Baker's agent David Hahn had received emails and phone calls from disappointed fans who had booked tickets for Mr Gubby's band expecting to see the original members, the hearing was told.
Ian Stocker, who runs a fan website, heard similar complaints.
But in his ruling, principal hearing officer Allan James said that the confusion was caused by the use of the name The Original Bucks Fizz.
He also ordered that any costs incurred by Heidi Manton during the action should be paid.
Baker, Nolan and Aston have already delayed the release of an album due to the dispute.