Call Number hijacked

My vodacom prepaid number was hijacked and the hijackers have accessed my WhatsApp account and sending massages to my contacts asking for money and pretending to be me. I tried calling costumer care and was referred to tobi which did not help went to the store to rectify the error but was dismissed at the store this is tarnishing my reputation at work because it seems that I'm asking for money from suppliers and going against company ethics on business partners interaction this is continuing and vodacom refuses to act on this matter