Shaeren McKenzie, Gossard's marketing director, claims to have fired the agency after clashing with chairman and creative director Trevor Beattie.
"TBWA and I have different views on lingerie advertising. I want to advertise to women not men, but traditionally the market has targeted men and I want to put a different spin on it, said McKenzie, who joined the company last October from the Arcadia group.
She said her priority was to focus on business objectives, adding: "I'm happy to engage in debate because that's healthy and of benefit to my brand and business, but it's not just about winning awards and creative kudos."
Garry Lace, chief executive of TBWA/London said: "We are happy to have parted company with Gossard. In the end, we simply couldn't do business with it. It is about to embark on its fourth agency relationship in 12 months."
TBWA snatched the Gossard account in October 2001 from Partners BDDH, which had held the business for four months after Abbott Mead Vickers BBDO resigned it.
McKenzie did not deny that the move to TBWA was made largely because Brian Duffy, then chief executive of Sara Lee Courtaulds, had worked with Beattie on Wonderbra's 'Hello Boys' campaign. However, she said the working relationship with TBWA had deteriorated since Duffy left in February.
Gossard's first TV ad campaign for ten years broke in May, promoting its Altogether range of underwear.
McKenzie said she was pleased with the creative result but "the process of getting there was very painful".
McKenzie has already invited a list of undisclosed agencies to pitch for the account. She plans to maintain or increase the £5m adspend for Gossard.