Cell C deactivated a number I had for 14 years

Cell C deactivated a number I had for 14 years (without my knowledge or consent), then gave it to someone else 3 days after I visited the connect center to reactivate it. Multiple phone calls to customer service and I'm told my number is not registered with the network. No response from emails. In-store visits were hostile, and the connect center said it would be reactivated. Now a stranger has my number and access to my private WhatsApp.