National Floors Direct review: failed to fulfill conract terms

We signed a contract for wood flooring on 1/11/2010. The contract states "BUYERS RIGHT TO CANCEL: You the buyer(s) may cancel this transaction at any time prior to midnight of the third business day after the date of this transaction." We cancelled verbally to the Sales Representative on 1/12/2010. We were told to write a letter and submit it to the Elkridge, MD office and we did. We have not received our refund of the $820 deposit. National Floors Direct claims that we did not cancel and will only issue a store credit. We have made numerous attempts to obtain our refund. National Floors Direct staff do not return calls and refuse to issue the refund.