refuse to refund

I go to CMH cape town 6th Feb 2015 to buy some parts. The clerk said some of it not in store. I need to pay and fetch those parts after 3 days later. I pay all the money to him. I go to CMH again on 11th Feb 2015 and told the clerk Justin that I do not one of the parts but the clerk refuse my request and give me the invoice and stamp a special stamp on the invoice. The stamp content is 'Return Policy'. That means the RETURN condition is limited.<br> <br> I said there is no such Return policy on the first invoice when I paid on 6th Feb. And I request the refund within 5 days and the parts still in the CMH store.I can refund the goods back when the goods is no damaged according to the South Africa law.