Telkom data contract

I had an unlimited data contract with Telekom.I have been going up and down trying to cancel this contract, I have not been receiving any data from them for over a year now. However, they have been billing me every month, I don’t know how to get out this mess, I have went to several Telkom store. I was told different stories .it is cancelled “or it will be cancelled in 24 hours, I was told this last year. And to this day they are still billing me.