Being billed for airtime i never receive

I cancelled my airtime subscription in July,2013 . My call was logged and service cancelled to my knowledge. My husband finally enquired with me as we are paying our account every month and the account is not going down. I then went to my local store and queried the account. That is when i found out they OTA as still being billing my account. I immediately phoned and the lady told that my service was logged for cancelling but they didn't receive conformation that the service was cancelled.Received a sms for Vodacom stating that my cellphone number has been converted back to prepaid. Explained it to the lady she logged it down said someone will call me and give me a ref number. This was on the 6/01/2016. A week later still no call, went back to my local store as it is to expensive to use my personal phone. they take for ever to answer. Spoke to another lady she said that someone did call but their was no answer. Left it at that and asked for someone to phone me at 15h00 as i will be home. To date no call. They have billed my account from July 2013 till this very month March 2016. That's 32 months paying R41.50 for airtime that i didnt get. I want my acoount refunded. very unhappy.