Webasto heating again

[Naughty Cal]

Our warm air diesel heater decided to overheat on Friday night to the point of melting the plastic on the outlet in the canopy. Didnt think much of it and thought we would just replace the flap and have the heater serviced. Had a quick look at it to see if anything was obviously wrong. The only thing we did find was that the air intake was a little blocked by dust. We have cleaned this but have not needed to put the heating on since so dont know if this has fixed the problem or not. Have just got off the phone with Burton Waters who want £500 to service the bl**dy thing and cant do it while next week. Which would be great if the boat was even going to be there. So any ideas? I would quite like to have some heat whilst on holiday.