[Aquarian Sports Cards]

Also from the description:

"This grouping comes from some of the very first PSA graded cards out there with nearly every card grading EXMT."

I'm no PWCC apologist, but the other problem is it's not their item to do with as they please, there is a consignor involved. They would either have to get the consignor's permission (which likely wouldn't happen) or issue you the partial refund and eat that amount when settling with the consignor.

A retail sale and a consignment sale are very different animals. They offered you a full refund, I don't understand how your trust was abused.