Refusal to cancel my contract Unit does not work.

My cartrack unit does not seem to be working as my car battery ran down on two different occasions and I got no call or notification of the unit being faulty, now when I am requesting to cancel with cartrack they want me to pay a Call out fee, They can't even provide me with a copy of my signed contract, I want to cancel and now they say that I cannot cancel now and that I need to pay a call out fee, to date there has no notification that the unit is faulty and now they want me to pay a call out fee.I want them to come remove their unit and cancel the contract with immediate effect. I spoke to Nthombi Motoung who said she would send me an email to date nothing received. Reference ***