Some of the six shops that won places on the DoT's go-it-alone roster, after it split with the Government's COI Communications, are worried that the heavy workload involved could eventually persuade them to quit the DoT list.
One agency source said this week: "It seems the department has decided to adopt a pick-and-mix system, with agencies being asked to pitch again whenever it wants to do a new campaign."
Another senior agency figure said: "The system isn't workable. Unless changes are made, some people are bound to decide to walk away."
The criticism follows the DoT's surprise decision to switch its high-profile £2 million drink-drive account from Abbott Mead Vickers BBDO, which had won awards for its work, to D'Arcy in July.
Agencies hoped that winning a place on the breakaway roster after a full pitch would bring them business without further presentations.
But DoT officials insist they had told shops they intended to operate a flexible approach to campaigns.
The roster includes D'Arcy, AMV, Euro RSCG Wnek Gosper, Rainey Kelly Campbell Roalfe/Y&R, WCRS and BMP DDB.
The criticism is the latest controversy over the DoT's decision to break away from COI, a move which helped to spark the resignation of Carol Fisher as COI's chief executive and Derek Dear as the chairman of the Advisory Committee on Advertising.