Relations between the two have been strained since Holsten called a review, through the AAR, at the end of 2002. TBWA managed to prevent the review from progressing last year, but more recently has failed to reach an agreement over its fee.
The TBWA chief executive, Andrew McGuinness, explained: "We have produced some fantastic award-winning work over the years and this is a tough business decision. We simply cannot afford to continue to run their business at a heavily discounted rate."
TBWA's most recent work - the "It's what's inside that counts" campaign - came under fire for being "insensitive" in its use of a woman with a facial disfigurement.
Over the years, TBWA has produced some highly regarded campaigns for Holsten Pils. These include spots featuring Griff Rhys Jones in scenes from black-and-white classic films and Denis Leary delivering rants on modern life. More recently, Ray Winstone became the frontman with the strapline: "Who's the daddy?"
Holsten has suffered from falling sales and, according to Nielsen Media Research, its current advertising spend is less than £1 million.
The relationship between Holsten and TBWA is also thought to have been weakened by changes to the management at both companies. Garry Lace, TBWA's former chief executive, left the agency at the end of 2002, while Andy Edge, Holsten's marketing director, quit in June 2003.
The marketing manager, Ben Peters, has since been promoted to replace Edge.