Telkom is over-billing me on my account

Incompetency within Telkom and their collections department is very high. I have a contract with Telkom which a pay a fixed amount of R200 monthly basis. My account was handed over to collections as it was in arrears. I owed R600 to Telkom, that is, R200 premium March plus R200 penalty fee for March plus R200 premium for April. All this in total is R600 due to Telkom month End of April. I called Telkom (15th April) and asked them to debit my account on the 25th of every month starting in April as it was 30th before, they updated their systems. I then called Collections and asked them to debit my account on the 25th of April. Collection debited R400(R200 penalty plus R200 premium March) on the 25th April and my account was handed back to Telkom since Collections debited what was in arrears and now Telkom should resume to debit R200 on a monthly bases as normal. Billing is sent to me, via email from Telkom and it says in need to pay RR800 end of May, I called Telkom and I was told my account is still with Collections and they couldn't even break it down to me as to how I got to R800, I called Collections, and they told me they don't have my account anymore as it has been handed over to Telkom. Where is my account and how did it get to R800 ? I will never ever advice anyone to open a mobile contract with Telkom, they overbill and never even bother to explain anything.