Poor service delivery

I upgraded my vodacom cellular contract in January this year and took a Sony Experia phone on a 24 month contract.But i started having problems charging the phone in late August. I went to the Chats worth Store to hand the phone in for repairs as it should still be on warranty and they sent it to Umhlanga for repairs only to have it returned unrepaired. i then took it to the Gateway Store in Umhlanga myself and was assured by the manager that they would take a look at it but i ended up with the same results. - Vodacom insists that the warranty does not cover the charging port!!! - This is unacceptable as this particular part is what gets used almost every day - and it is not covered under warranty?? -I receive an e-mail from the manager stating that there is nothing that they can do and i must take it up with Sony. But i am still paying Vodacom for my contract. Unacceptable.