Poor service at pep store Golden acre

This evening I purchased a R500 1 for you voucher at Golden acre pep stores,they rang it as 5 R100 separate vouchers despite me asking for R500 one,I told them I don't need it like that as I need to load it for my trading account as the minimum amount for me to load is R170 so now I'm sitting here with useless R500 voucher that I cannot use .I asked them to change it they told me it's impossible for them to change it.