Dishonored Voucher purchased

I bought a planet fitness 3 month gym voucher from dischem only to find out planet fitness does not take the voucher any longer as a result I tried on four occasions to get planet fitness to recognize the voucher after which I went back to dischem for a refund. The manager from dischem Westwood called planet fitness to verify this and was told the same and then he tried to reverse the voucher which costs R899. The system would not allow this and I am not out off R899. Pathetic dischem. I am consulting my legal advisor on the next step as dischem should not be selling these vouchers.