Unusable Voucher

I am really unimpressed with the service at Tekkie Town Mafikeng. I bought sneakers a couple of months ago which I had to exchange for a smaller size which was R100 cheaper. Instead of getting my R100 back, I was refunded in a firm of a voucher and was told I could use at anytime.

I few weeks later I went to lay buy another pair, then I was told I couldn't use the voucher at that point but only when I was collecting, fast forward to collection day........ You can't use a voucher in a lay buy. When I asked what I should do with the voucher, I was told to find someone who would use it and give me R100. I am really unimpressed with this store.