Telkom taking unauthorized funds from my account

I opened an account with Telkom in the December last year and it was the worst decision of my life,The contract is R800.00 and they've been debiting me for amounts of R2500 and R4800 and when i go to return it they change the amounts.Ive been sending telkom emails and calling but no one ever gets back to me,I was told my matter is with management but no one has ever contacted me and they keep debiting me.