I don't agree. If I have a legit booking at a set price, I don't care what tax was passed either before or after my booking (contract with the agency).
That's the price of doing business. A contract is a contract unless it stipulated that the fare might change. If that were the case, I would have moved on to another TA.
SS Norway (12 times) '85 - '97; Radiance OS 06/01; Island Princess 11/04, Grand Princess 11/04/05, Golden Princess 7/21/06, Golden Princess 2/24/07, Explorer of the Seas 12/23/07, Island Princess 11/15/08