Quoth clause 16 of the H&R Block Emerald Prepaid Mastercard Cardholder Agreement: "In the event your Card Account is canceled, closed, or terminated for any reason, the unused balance will be returned to you via a check to the mailing address we have in our records." If that hasn't happened to you, recommend filing a dispute by mail per clause 17, opting out of arbitration per clause 18, and reminding them of that.
I am not a lawyer.
One need not be a lawyer to understand that means a check will be issued. OP got no check issued, so they are not upholding the agreement.