There are many one way contracts. ..car rentals, cable tv, , buying a new house or condo from builder/ developer in Fl.. no changes allowed .
Fairness and justice are on the side of OP who seems to be nice about it.. he has no choice!
Note:
An adhesion contract is a legal agreement that is drafted by one party, but not the other. This means that the party signing the agreement had no chance to bargain for the agreement's terms. Instead, it is a “take it or leave it” situation.
Only thing OP could do is set the amount of the bid.
I am so happy we do not bid..and try to stick with what we initially booked.