Bad service on Gift card.

I bought a gift card at makhams at pritchard street and assisted by lady called Lorraine. i went to buy some clothes in sandton using the gift card only to find out that the gift card has a zero balance in it, so i dont know what Lorraine did to my money and i still have the till slip but now i want my money back since i ended up using my own money because the gift card had insuffient fund and sandton store dont want to help me, they say i must go back to where i bought the gift card from.