Poor service and Item quality

I bought a bicycle head lamp for R699 at Solomons Cycles on 25 April 2015 and in May 2015 it was already broken even if I don't use it everyday. I took it back for repair and I called after about 3 weeks without hearing from them. It was then replaced with a new one that also stopped functioning. I also took it back and was told it would take a week and a half to be fixed. After two weeks I called and it was still not fixed. I then asked to be refunded and they agreed on the phone. I went to the shop and a man by the name Riedwaan refused to refund me coz I bought it over 3 months. He wanted to replace it with a new one and I refused because I want a refund. If the lamp he wants to give me is worth R699 why does he not want to give me money. I don't think that their lights are new because all the 3 boxes were already open.