Cell C is *****

I had R1901 in total debited by Cell C without my permission and I went to Cell C store to query about it and i was told that someone opened an account ( contract) and took iPhone 8 using my details, I asked them how is that possible, they don’t know but they will investigate, and i was told this things happen if your name is clean, what’s up with that?I open up a case against them for being careless and when they contact that number it doesn’t exist anymore. Please help!!