I never signed up for that contract !

I noticed in October that there was an additional number on my Vodacom account and the bill for September was already over R700. I never signed up for any additional contract, never received any device and don't have any additional SIM to even use that number... so I visited a Vodacom shop who referred me to Customer Care. I called them and reported the issue - they said they would "log a call" and cancel the subscription. It's now weeks later and I still see that number, which I never signed up for, on my account... and the bill is headed to R8000. Someone is using it, but it sure isn't me. This is so stupid - I'll have to reject the debit order and manually pay the legitimate part of my bill, then hope I don't get cut off because of the so-called "outstanding amount". And I'm not getting proper invoices or statements out of Vodacom, despite signing up for email billing and reporting the missing statements & invoices repeatedly. I've now asked for my contract to be ended so I can go onto pre-paid... and after 23 years with Vodacom, I'm now seriously considering changing providers. Vodacom billing is the worst !