Charmglow Ventless Wall heater stinks - Lit...

I bought this heater a year ago and had it installed by a professional. It smelled awful when we fired it up, but he said it would burn off. After a few days, it still smelled, so I quit trying. Here it is another winter, and I'm angry at the money I've laid out for the purchase, installation, and trouble calls. No one seems to have any ideas, and you can't find any info on the Desa website (from the side of the box). It doesn't even list the owner's manual, which I've lost, of course. It doesn't sound as though it would help very much even if I had it!

The model # is CGL300TB, and the serial # is CGO5018885