No intergrity

I have a unit which stopped working of which I phoned to let Cartrack know about. They were efficient in organizing someone to come see what the problem is and he indeed 'sorted' the problem out. A week later I'm told I need to pay R600 call out fee of which I never agreed to. That is very unprofessional of Cartrack and until proof is sent to me that I indeed agreed to pay, I will not. so dissapointed