YEARS OF THEFT

I purchased a phone for my mother years ago on contract, when the contract expired I cancelled it with Nashua Mobile, when MTN took over from Nashua Mobile I discovered that I still got billed for the number that is not in use, I tried to contact the customer service which is not customer friendly and ended up going to the Richards Bay MTN branch to cancel this contract. I received a reference number I sent countless emails to the customer service and no one has come back to me. It escalated over R3000 for 5 years - I do not know of anyone who can just take money off a persons account without their consent. I received a bill again this morning after being assured that this is sorted out and to be honest I am fuming. I hope you can help my I think it is time to take them to court for theft because their customer service lack communication skills