Some of you may have been faced with an issue of missing taillight caps, genuine part.no. 7L6945285.
You're free to order one such piece (or more) from any source, including the dealerships, but the prices aren't low (starting from around 4-5 GBP a piece - yes, a piece, not a set). You could try and obtain them from a breaker yard, don't know about the price (and they're used, possibly at least one broken clip, etc.). What if I told you there is an extremely cheap alternative, that beats the genuine part in both quality and the way it clips to the taillight, and requires juts a little bit of DIY (cutting the extra plastic, because the original cap length won't allow you to push it in place in the taillight). Well, here it is. In my case, out of 4 in total, I had 2 caps missing, one was genuine, one was something who knows from what. Anyways, what you need is this:
https://www.aliexpress.com/item/22mm-Diameter-Round-Plastic-Blanking-End-Cap-Tubing-Tube-Insert-5-Pcs/32807481896.html
The price is currently $0.63 for a set of 5 (I've actually received 6 caps) and free shipping worldwide. You just need to cut the extra plastic (after the first thread) with a scalpel or a similar tool (watch your fingers) and after that just clip in place. Perfect fit, better that the genuine part (clips all around, not just by having two flimsy hooks on each side), they actually fit so tightly, I don't know how I'll get them out if I'll have to