Well then you have a fair right to be ticked off. 
Maybe they are just stalling you waiting for 
another auction to be completed to free up funds.

Or maybe they simply are trying to get out of it. 

As for me, my pet hate is similar but from the 
buyers side (and I understand that you didn't do 
this) but when you win an auction, and its cheap 
and they then try to jack the postage up to make 
up the difference. (and I say again this is not 
what you are doing).