Removing a qualification

I decided not to take my Government and politics AP test as my conditional offer did not include it. I also reported this change to UCAS in an email but I never got any response from them. Today I read in my offer pack that the university will withdrawal offers from people that don't tell the university that they are dropping a qualification even if it isn't part of the conditional offer. The problem is that there is no way to sign back up for the test now and it also said in the packet that If you do notify them they tell you whether or not you can drop it, so they could say that I can't and I would be screwed. What do I do?