METRO PCS UPPER DARBY STORE 7609 Charged wrongfully my account for a phone they never gave me UPPER DARBY , Pennsylvania

I went to a Metro PCS store on 12/24. I asked for a phone to replace the my son's damaged phone. They failed to tell me that a warranty replacement was available and started selling me a new phone. 

When I realized a warranty was available I asked them to reverse the transaction they had started, they flat out refused. I kept the merchant copy and the customer copy. I left without the phone. They then submitted a bill to METRO PCS against the phone account. As a result the account has a balance for the amount of the phone number. Because of this balance, they have shut off the account for which service has been paid.