Yes I would also recommend trying the dealer first. If you don't have any luck with them, it may be worth going to an auto electrician just to check that it is the light unit that's faulty as it may be a poor earth caused by the condensation.
Good luck with the search Nixy. The sleepless nights and chewed finger nails will be worth it. All you will have to worry about once you get it is the inane grin you will be walking around with for months.