Does anyone have any ideas on how to deal with the poor performance of a vendor? We paid a lot of money for a band, and they kind of screwed us over (didn't play half our must play songs, played one song twice, took a huge break during the night that they weren't supposed to, messed up the whole end of the evening by trying to end early, etc.). Now they are being horrible about our request for a partial refund...do I just give up?