*****ulent contract under my name

Someone used my details to take out a Vodacom account, I had no knowledge of this until I got my credit report last month. I’ve been calling the call centre and ***** department but no help. They keep telling to go write and affidavit and I’ll get an sms telling me where to send it to but it’s always a dead end… This is affecting my work as I’m in the financial sector and I can’t afford to have such bad report on my credit score!! Can someone just help me get this matter resolved!!!!