Pep store golden acre cape Town

This evening I purchased a 1 for you voucher at pep store golden acre for R500 and the rang it as R100 x5 vouchers I told them I can't use it like that as I needed it for my trading purposes,and my minimum amount for me required on my trading is R170 so those R100 will be rejected.The manager told me she can't change it.Im now sitting with R500 voucher that I can't use.im very disappointed at this store.i asked them where can I go change it where are the office for 1 for you they could not assist me .