Refusing cash refund of defective goods

I bought 2 backpacks at Edgar's Active Promenade middle November however the Reebok bags stitching came loose and my daughter only used the bag to cart around light goods when she had gone to the beach or hiking. She used the back about 4 times since the date of purchase and last week after using the bag she showed me the loose stitching, I went to Edgars today to take the bag back and the store manager Miles refused to refund the cash money for the bag and insisted that I need to take something else or a gift voucher, I said to him that my daughter was not with me and he could rather give me the money back and she could come and see for something else another time, however I don't want a gift voucher as she might not want anything from there after this bag broke, he then said no he cannot give me the money back and said I have to take a gift voucher, i then said that it's not my fault that the bag is breaking and deemed defective and in a sarcastic tone of voice said it's not his fault either and he would have to send the bag away for investigation as this is the first bag thats come back to them where it's being said the stitching came loose and it would take 3 weeks before giving me feedback. I then said well send it away if u think that I had broken the bag. Firstly his attitude towards me was as if I broke the bag they way he spoke to me and secondly there terms and conditions says a refund or exchange will be done on defective items within 6 months of having the item however he continued to insist that he will not give the cash back for an item that is defective within 2 and a half months and this is one problem u would always experience with Edcon, there policies says one thing, and they very polite when they take ur money, but when they need to give money back it's always an issue however they do not adhere to there written terms and conditions. I'm totally disgusted with the managers attitude and the fact that Edcon contradicts themselves on there policies of refunds. He was not accomodating at all but this is the norm at Edgar's Stores and there for I hate buying from them however my daughter saw the stuff she wanted there and that was the only reason I got it there, but with this incident that took place now, I will never purchase anything there ever again and believe me this type of service is only given in the coloured areas...Very upset customer...