Premier Gymnastics Club, Inc

We installed a brand new battery in his vehicle in September. months later he comes in and informs us that we did not put a battery in the vehicle but he he did not bring the vehicle back to us so we could take care of problem. Instead he went somewhere else months later, purchases
another battery and says he does not have the battery we installed. We explained to him that he should have come back to us for any adjustment and we would gladly work with him but we need the old battery returned so we can get credit from our supplier. and finally he drove the vehicle for months before he called us, what happened for months?? We have a percent customer satisfaction policy but we feel this person is trying to scam us. If he brings back the old battery we will refund his money. Thank youTell us why here