Autozone's Lying sales people

I went to the Autozone pretoria central with a car that was having problems to start. I was not sure what the issue was. One of the sales people tested the battery and said the battery seems fine but could be because I was driving the vehicle. Because they car is still fairly new the saleslady together with 1 of the mechanics there advised that I buy a new battery as it is obvious that it can't be the starter. I enquired about what would happen if the issue continued after purchasing the battery but was quickly assured that I can bring back the car within 7 days with the receipt. 2 days later the issue started again and I informed autozone that the issue had nothing to do with the battery and I needed my old battery back and my refund as was promised only to be told that they no longer have my battery and I won't get a refund. I was clearly cheated by this *******. Be warned