Chippy; you, sir, are an unhelpful ignoramus. You sound so self-sure that you know what/who caused the burn.
But then, you won't know that friends of teenage sons or daughters could do this type of damage, as you obviously have no kids yourself.
As for your 'If the plastic has melted, tough' statement - that sounds just like you, you dick.
Christine; I had damage on a motor home, what you need is brilliant white upvc gell, hardener, acetone, very fine wet and dry also lots of elbow grease. The last you will have to supply yourself but there will
probably be a fibre glass business or a motor home "doctor" near or even a ships chandler, if you are near the coast or a canal, from whom you can scrounge the other items.
I then masked around the damaged area, cleaned well with wet and dry then acetone, applied the gell mixed with the hardener, a little proud, then covered with polythene (it goes off when not in contact with air).
Next day remove it and the masking tape,
apply plenty of elbow grease using the wet and dry then polish with T-cut.
Kenny, March 2013