Help On Many Levels Required

[Smurf]

Dont print this thread out and show it to the warranty people cos you have said that you havent maintained it since buying it, they will deem your warranty void. Sounds to me like you have an airlocked cooling system if it is blowing hot then cold from the heaters, get the coolant topped up and run the engine with front and rear heaters on hot, squeeze the rad hoses to help push out any air and keep doing so till both heaters run hot.
If you still have a problem after that then take it to the warranty people and explain that it is overheating.
Good luck, hope you get it sorted.