Cell C review: My number is registered under someones details I can't do sim swap

I have been emailing asking for assistance regarding my number [protected]. Today I went to the Cell c Store at the Grove Mall, I spoke to the assistant manager Jean-Piere and I explained to him about my issue. He said that he cannot help me with the sim swap. The policy does not allow him to do a sim swap for me. He then advised me to email the customer service again and ask assistance to bypass and fix the issue and get my number back.
I have documents including my company invoices that can show I have been using this number for many years. The person registered under my number is a foreign guy with false details. There is no contact number under his profile that can show that my numbers belong to him or not. I believe that is valid enough evidence that proves that the person registered under my numbers does not exist or doesn't even know my number is registered under him.

I don't know what else I can do, even agencies can't help even the store manager are refusing to help me. Can I at least get the team leader who can help or even the head of the department? I have all the documents that can prove I have been using this number for years. I am not scamming nor fraudulating Cell c. I can testify to that.

I hope this time around I will get a call from someone who might help me.

Kind Regards
Sinazo Nxedlana
[protected]