Invoiced for number I don't have

On 7 January a Vodacom rep phoned me to ask about accrued airtime for a number I don't have. Apparently, this account has been active for 4 years, billing me monthly, but I've never owned such a number or contract. I phoned the call center to query, who refused to help me and said I go to my nearest branch. I queued there for about an hour, finally got to a very helpful gentlemen who logged a service request (S3-GJFAI-IRZ3). He advised me to get an affividavit and a copy of my ID to upload via [Email Removed] I did this, and then heard nothing for 3 weeks. I phoned the call center who said there is no record of this complaint or service request and that they can't help me. I'm 7 months pregnant and really not in the mood to queue again. I don't understand why it's so difficult for Vodacom to find out why I've been billed in excess of R10,000 over the last four years, without any resolution? And why, if I'm holding the service request in my hand, is there no record of this complaint?