Voucher funds paid for but not available for use of gift

I purchased a gift vouchers for R500 and this expired 31 December 2023. We have tried everything to use the voucher but it kicked us out and we could not Purchase anything and just to find on the 31 December the R500 is not loaded meaning there was nothing available to purchase from. The Number of the voucher is NABKKBWCLHRHFPKP and to try and have this resolved is difficult as I have emailed so many times already to ask about this and no one is coming back to me.