Hi - I have a background in electronics and computer repairs, tech support. (ie logical thinking) Whenever I look through a thread like this I look for the bl**ding obvious.
I may have missed it but can you swap the two headlamp bulbs over?
If the fault follows the bulb .....
= £110 "only"! I didn't see anyone suggest this.
The only risk would be that in handling the lamps you may damage them and hence start all over again.
BTW can't fault "Sports Tourers" logic.
PS Sorry just noticed this has already been suggested ....