Hi
I think I need your help

I consigned my Mother's Black Diamond Mink Coat with a consignment shop here in Maryland last September 2009.
Their price policy is After 60 days the item can be discounted and their payment policy is checks are written and
mailed out the first week of the month following the sale..

The consignment shop said they sold her coat for $400 less then the agreed upon price claiming it had been there
more then 60 days. However, they also claim mailing me a check for the sale early in November, which I have not yet received.

If the check was mailed early November that would mean the coat was sold in October, well within the first 60 days and probably not discounted at all.

QUESTION: What rights do I have to protect myself and to find out what the coat truly sold for?

Any feedback or guidance is deeply appreciated as I don't know where else to turn.
Thank you so very much