Life threatening risk!!!

Installed a unit on my wife's car and it malfunctions,we call and they want to charge us to fix the unit,after a run around, suddenly the contract is about to expire,they suddenly offer to replace it for free!!! now its malfunctioning and they want us to pay AGAIN!!! Why does it keep malfunctioning??? They want us to move to another pakage thus pay more money for something that we already know is going to malfunction. You are running a shadey operation and what worries me most is the fact that its a female owned car but we get such unreliability and attitude from the consultant!!!