Money back

I purchased a gift card from istore Menlyn and I want to buy a watch and I’ve paying it every month then Vodacom cellphone contract offered to give the on contact that I have to collect it today so now I called Menlyn store and head office they refuse to refund my money and I don’t need anything I just need my money back I don’t need the gift voucher anymore now m stuck with the card they say I must look for a person who can give me money n pay for the goods …..wow imagine thise is very frustrating