I have the same problem with one of my HIDs too, I sometimes have to wiggle the wire to it and it will then work for a couple of weeks.
@ itsmeagain : I wouldnt be ordering any HID kits etc yet, just make sure you get the motor sorted. Like James says, Its a big Risk travelling 150mls back to the dealer if the worse does happen so discuss the options with the dealer, you never know he might be understanding but im guessing he is going to want the motor back to himself so he can check it out with their regular mechanic (...probably so he can save himself some money rather than going to another dealer somewhere else).
Im guessing that the Cab was sitting for a while over the drastic cold hence why your battery has had it. Also with it standing a while (if it has been) then it probably only just been turned over few times and left running then you buy it and give it a good Raping on the motorway, if its got ****** oil in it (...or hasnt had a decent service for a while) then your heading for the dreaded sludge problem. I dont want to sound negative but even if the light doesnt come back on for few weeks, It WILL eventually. Do your research tonight on the issue and be prepared for when you speak to the dealer because he will probably try and talk a load of Speel to you, at least then you can hit him back with the Facts rather than go in Blind. It sounds a good Idea to smack him in the mouth but you dont want to make the situation any more uncomfortable for yourself. Keep Calm and like they say use the "sales act" with them and make sure you make it loud and clear.Stand your ground and take no Crap.
Let us know how you get on, it'll be interesting!!:icon_thumright: