Having dealt with this WAY back in '94 or '95 with my school it was the opposite they would take VI and AX but not MC. Back then the school had negotiated rates with their processor and bank. Over the summer MC raised some rate and the processor went back to the school who promptly told them to stick it. The school then published the entire exchange of documents in the school paper apologizing to to students, while pointing out that although a 1/4% was not a big number at the end of the day it would have cost them a bunch.

Close to 15 years later the same BS is still going on. Nothing changes.
-Dave