Frustrated and Dissapointed

Bought a phone cash at Vodacom Chatz in May 2015. Since we got the phone it works for a couple of days then it doesnt want to charge. We took the phone back. Battery was replaced. A week later.. still the same problem. We went back and battery was replaced again. Again we went back. They sent the phone to cresta. Phone came back. Still same problem. I called Leon at cresta. He said I can drive to cresta and he will motivate replacement. I was advised phone is back. Went to cresta on 05 Dec. They only changed the battery AGAIN... Vodacom was quick to take the cash. But we had no use for the phone yet.. What do I do now ????,,,,