My heater is on FIRE

[panelbeaterpeter]

Hi all, not been on here for a while, had a B3, but now have bought a B5 saloon. It's pretty good, apart from there is a very bad strong smell coming from the heater when you put it on hot. It smells a bit like burning plastic, and really gets stuck in the back of your throat, so I obviously don't use it. The guy I bought it off said he never used the heater so it could just be dust, but I've had it on for about 15 mins and it stays the same. Also the re circulation air button on the heater controls doesn't work, I doubt if that's related, but worth mentioning. The car is a 20v petrol, standard spec, no air con or anything fancy. Anyone got any idea what could be causing it?

If I need a new heater, then so be it, but I'd like to know before I start ripping the dash out

Cheers, Pete

P.S. Apologies for the slightly melodramatic thread title.