How can you charge me for something I didn't sign for

Telkom SA. I Went to Telkom store mall@55 to top up on my cellphone contract. My cellphone contract is 499 for 2months. Come November 30 Telkom deduct R1028 when I call to ask now I have a contract for home wifi that I don't remember signing any contract for it.. my question was why is this from my name. The promise to investigate and refund me back. I receive a telkom case no after a week it was close but no money was back in my acc.. I call several time go to the store no help. Come 21 Dec R2339 gone again to Telkom , still the same process , now yesterday 24 Jan R3223, gone gone again . Telkom you are a big company but you service is very poor now I'm receiving a message from attorneys that I'm owning you. I thought telkom was the best but a ****... please I need this matter to be resolved it's been 3months.