Burning Plastic

[toy_yoda]

My 2001 Toyota Avensis is giving off a smell of burning plastic when I turn up the heat dial. This smell is quite noxious and seems to be coming from the pipes behind the centre console. I have checked this area and found that although it gets quite hot there is no obvious melting points. The only thing I noticed was the black rubber wall behind the engine bay on the inside of the car was touching off the heating pipes. Could this be causing the burning smell? Toyota have checked (eg drove the car for twenty mins) and said they could not smell anything. Any ideas? Has anyone noticed this before? At the moment I cannot use the heater because of the smell/fumes. Thanks,