Telkom accounts department is rude and false

I have a contract with Telkom. In December they made a mistake with my account and said I was in credit so only debited a small amount. I went in to one of the shops to cancel my wifi and the lady told me my account is in arrears so she cannot help me. Then assisted me to contact their accounts department. Where I explained that they cannot switch off my services because of their mistake but I would be happy to pay a certain amount extra each month to make up for the money they said I owe. They refused and refused to accept that it was their mistake. Now they have stopped my service and won't assist me. They also gave me the run around with I have to phone other parts of accounts. Very rude, don't take responsibility. Dont assist. Also there is a device on my account that I am paying for that I don't own.