Paying for a non existent car

I have four cars with Cartrack, on a 36 months contract. Last year December my Ford Everest Limited was flooded when visiting the villages in the Eastern cape. It also turnd out that teh tarcking Unit died on the 25th Nov and the Incidnet happened on the 18th Dec. we have gone through the process and the car is now written off. By the way Car Track indicated that I should pay R600 for the repair on a dead car, anyway that is how they do business. What shocked me is, I am still expected to serve a 20 working days notice for cancelling a contract for a Non working Unit on a written off car. I am flabbergasted!!! Fortuantely or better, the contract is over 36 months on this car, otherwise I was going to pay an early terminatin fee for a non existent car and a non wking unit or pay monthly premium till the end of the contract...Be careful fellas