Ackermans refund

Today I went to Ackerman’s Hoedspruit to get refunded for the school bag I bought from them last week, because I bought one online with that is much better than Ackermans bag, was told I can’t get cash refund only gift voucher, but then it stated on their till slip “we will gladly refund or exchange any item in a saleable condition within 30 days, provided you have the original till slip, refund or exchange after 30 days without original till slip will be given on a gift card or exchanged at the current system price” In this case I had my original till slip. So please why are you misleading your customers. I want my full refund either cash or refunded to my bank account.