it is running and cold air is coming out of the exhaust and then it shuts down

Looking for advice on how to fix it myself, if I can't fix it myself I will then survive With a broken one

Copied it for your reference.....curiously i dont have post numbers displayed now either.Still working on it.
Info from Webasto Doncaster: Upgrade kit part number 89247D, comes with water pump (circulates coolant through matrix), water pump adaptor, 1hour timer kit, harness, formed hose(i assume to go from circulation pump into heater matrix), clamps, electrical connectors. Price £296.45 Forgot to ask if that was inc vat...doh. links below are for further reading as im at work and cant email back to home at the moment but others may find helpful.
http://www.techwebasto.com/heater_main/907512.pdf
http://www.techwebasto.com/heater_main/5000918A.pdf
http://www.techwebasto.com/heater_car_light_truck.htm