Mweb customer service is bad...

I have tried the call centers, I have tried logging requests through the website and yet I can't seem to get my problem fixed. I don't know why I have to resort to HelloPeter for this. We have cancelled our line. We want Vumatel. Vumatel is saying they can't proceed with the connection because they get this error:

"This location has a running service with another ISP. You may not manage this service."

How can I go about getting Mweb to release the line? This is urgent.