Overpayment and unauthrised cansellation

In Dec 2014, I noticed the netstar unit in my vehicle was no longer working. I contacted Netstar and was informed I needed a upgrade. This was done in Dec. Jan and Feb was debited for 2 units as the old unit was not discontinued. After weeks of trying to speak to a accounts person and emails, I was informed the account will be corrected and the money paid back. 1st March I was debited a cancelation fee and the contract cancelled. Nobody can tell me by who or why.