I was driving back from Portsmouth up the M27 when i got a coolant warning on the DIS, i checked the temp gauge and it was sat around 110, after about 10 seconds or so it shot straight up to 130, and the car steamed up immediately as if the aircon had turned off. I pulled onto the hardshoulder and switched off the engine, and checked the coolant level, it was sat right on the MAX mark. I left it about 5 min and started the car back up, and the temp gauge was sat at 90, so i carried on and then the temp went up to around 100 again but did not get any higher. I left the car for an hour and started it back up and the temp was about 70, and now i have no heat coming from the heater even when set on max. The car is a 2004 a4 tdi 130, and i have never had any temp probs or coolant level probs prior to this, i have searched but cant find anything like this. Please help me!!!!!!