Unauthorized port of my number to Cell C

I received a call from a lady that claim she represent Vodacom and she received a request for a SIM card swap. I denied it. I did received a Vodacom sms that said the same. I tried to call Vodacom client centre with no revile. Just to found the next day my phone has no service. I visit the Vodacom client centre at Menlyn. Just to find out that my number of 15 years was ported to Cell C. I tried to regain my number but I have to make an affidavit and have to wait for 5 working days. I request a new number. But tried no numerous times to find out who gave permission to port my number. I am only referred to the call center with no HELP at all!!!