1 star is too much

Two years ago, my cellphone number was ****** – a so-called SIM swap. I've been trying for 24 months to convince Capitec to remove the ****** number from my customer record. Despite various emails, visits to the customer service center, etc., I've been unsuccessful. Not only is the number still in my master record, but it's also a security risk. No, Capitec keeps claiming the number has been removed. Today, they closed the case because they tried in vain to reach me on the ****** number. At the same time, they again stated that the number has been removed. I sent hard copies again. All in vain! How do I get a reasonable employee, or do I have to cancel my account?