Telkom wants to list me as a slow payer but their system doesn't initiate the debit order on my new banking details

I've been at a Telkom branch 3 times, first to update my banking details then the debit order didn't go through. Went back to verify that it's correct and asked for an agent to contact me, never received a call. In this week I received a call from a debt collector that still had my old banking details. I also received an sms from Telkom saying if I don't pay they will list me as a slow payer which will be bad for my credit record. I went back to the same Telkom shop, Banking details are correct, they couldn't help me and asked for an agent to call me, still no call and 2 weeks without internet. How could the system of a big company be that broken?