Telkom

I took out a 24 month cellphone contract in 2014 with telkom. After the 24 months i was still being debited i then went back to the store and i was explained how to cancel the contract and i did as i was explained. Yesterday over R1000 was debited by telkom after i havnt been using thier services since 2016/2017 for that same account that according to my knowledge was canceled years ago. Is there any advice or help i can get to try and get my money back i feel that it's very unfair for me to pay for something that I didn't make use or nor recieve since the contract had been canceled.