Bad service provider

Last year my phone was lost and my telkom clsim card was on the phone the next day I went to telkom to report that my phone and sim were lost they then told me they have suspended the line since someone bought thing on play store for R3000 with my SIM card, I then told them am not the one who bought it they said I must pay since it was done under may name, I then went to the police station to write a affidavit but still they say I must pay the money now am the credit says R1000 I don't know it got there, coz my monthly payment was R100 Before the **** telkom had my bank details another someone's name, I had to go and change it. Now that is affecting my credit score, I can't pay for something I didn't buy, they can't evn proof if it was me. Telkom