My number was hacked

I had a complain with cellc network. My number was hacked on the 24 April and stopped receiving, making calls and sending the messages but it work on watsup only. I tried to go to Vodacom store and they send me to cellc as Vodacom discover that it was now taken by cellc network. Cellc send me from pillar to post. May I kindly be assisted as I was using this number from 1997.