Unauthorized debit from my account!

My name is Yolanda Tima ID No ***: i took up a tracker with talk sure never did i agree to the subcription of an additional R49 per month extra to the R125.00 agreed to for the tracker. I have noticed this for some time till i googled and found so many people with same problem and that it is linked to this tracker. i would like this deduction to STOP ASAP, i am very close to cancelling the tracker agreement i have with you too. i want my money back.