This does not surprise me in the slightest! In fact, amazing its lasted that long even!
VW have used a twin filament bulb which, apart from the cap, is identical to the old stop/tail lights of old (ref 380 or 382 if I remember correctly). With those the 21w filamentwould blow and the whole bulb turn 'black' (a sure sign of overheating) and that was with the bulb being lit for short periods at a time (only when the brakes were applied).
Functioning as a DRL, it's on all the time the engine is running (21w in daylight, 5w at nighttime) - so no surprise its lasted only 12 months. Why have VW not used an LED for the DRLs?
So definitely, NO case to make a claim against the garage. I am expecting to be able to change mine myself- and that reminds me, thank you, that I must go to Halfords to buy a couple of replacement bulbs to have in readiness.
Edited by: PeterWestSussex