Failed participation with details

I recently changed my banking details with Telkom and phoned their accounts department in order to update my details on their side. As the call proceeded we finalized my details update and inwas assured debit order will go of on my new banking details. Debit order date came and the debit order went of on my closed old account. A few days have passed an no one has contacted me yet. I then received an sms stating i owe them around 5k which shocked me as my monthly installment is about 900. I then phoned in and got cut of the first time and then phoned again only to be told that it my details was never updated and that the actual arrears on my account was only 1 month's installment. After making it clear that it was their negligence that resulted in the missed payment they told me i am responsible for all costs incurred and as result i owe the previous bank their collection fees as well. My internet has now been cut of due to a Telkom Consultant who failed to update my details and as result i owe them and the previous bank funds.

I requested them to rerun the debit order and still nothing has happened.

Definitely not recommending their services..