Unwarranted Penalties and debiting when they feel like debiting.

After deputing my Oct Bill due to *****, Telkom decided to debit after I reversed the debit order. I then settled the amount around the 7th of November, a few days later. Now the only thing I owed Telkom would be the November bill of R849.40. Now come December they do not debit the R849 until the 8th of December for what ever reason. I call to confirm what I owe them seeing that I migrated to Prepaid a month ago and now they telling me I owe them R1000+ in penalties, from where I don't know. They quoted T&C which I have never seen. They can't even send me the contract I signed but refer me to general T&Cs which may or may not apply to me. What must happen to get rid of Telkom from my life.