Angry customer

Cartrack is a disappointing and unprofessional I had an issue twice there after it happened again so within 5 days I did a cancelation because the device was not working so they canceled my subscription which was alll good only until I get phone Calls and emails stating that I owe R125 how is this possible the device didn't work why should I pay it I mean I can but I wont it doesnt .make sense this is so unprofessional for such a big company really really disappointed and I keep calling them to explain but no on understands anything