Failing Tracking Unit and Undisclosed Terms and Conditions

Extremely disappointed! My car tracker unit is not functioning and I finally am told it is because the car needs to be started every three days or the unit fails. Why was I not informed of this condition beforehand - I would of never taken them if I had known! I travel for work, weeks at a time, and was NEVER made aware of this major limitation!!! It is not disclosed in their terms and conditions (I checked) nor on the call I had with them when taking the contract. I was told that the unit will keep failing every time I travel (which is often). Furthermore, each time it fails they want me to pay R600 for a repair. I have been on the phone with them for the past 3-days, escalated this countless times and have basically been told it is my problem. How is it that a business can get away with this? Surely they need to inform you from the start that in order for the unit to function please ensure the following is done (that was NEVER happened!). Why am I being forced to pay each month for a service that will never work for me???