Tracker Unit not Working/Responding

I have a 3 year contract with Netstar, dating back to May 2015, of which is expiring this year May. With the contract it was said that it has a 3 year warranty. Type of Unit fitted is the early warning with a panic button. Panick button is not working, and when I called in to test the tracking unit, they said its not responding so it needs to be fixed. Ok, im cool with fixing, but when I call them again to follow up, they said they will not be able to fix it, and I have to upgrade the unit. I dont mind upgrading as well, but I was told I have to take another 3 year contract.. How is that even fair because on my contract you stipulated that it has a 3 year warranty. I stil have 5 month left so it needs to be fixed. REASON why I don not want to take another contract is that I cannot trust Altech Netstar anymore, and I dont feel safe using them, hence I wont take the updgrade, But for the remainder of the contract I needed my unit fixed as per the contract.