Telkom have ****** over R4000 from me over a year.

I cancelled my Telkom line over a year ago, and yet they have continued to charge me. They have now overcharged me by over R4000. I have made them aware of this through emails, phone calls, store visits and social media. They always say they are looking into it and yet nothing is ever done and I now receive no responses. In my mind, this is theft. You cannot debit money from someone's account after a service has been cancelled and the cancellation has been reported repeatedly. It's disgusting.