Payback my money.

I had a contract with this company and I paid it up fully. I phoned the company a month prior to the last day and got a confirmation that the contract will be cancelled and my last payment is on the deduction date on May. Until they deducted again in June and I still haven't been given an explanation as to why was my money deducted when the contract has ended. I called and the lady I spoke to also advised that she is not sure what the charge is for. I have a confirmation for a chat I had confirming my last payment and closure of my account. Please pay back my money. When my sim card was being converted to prepaid, I lost all the airtime I had at the time.