Faulty cartrack device for 3 months debited for 3 months of no service,wants to charge R600 to come fix their faulty device

My device has not been working for 3 months,but cartrack has been debiting me for those 3 months I never received any call to inform me about the faulty device for those 3 months,the worst part is that they want to charge me R600 for fixing their faulty device

I have been paying for no service for the par 3 months 184 x 3=R552