These look fantastic!Had my "U" DRL go out as well. The ballast was the issue. I'll have to dig around and find the one I ordered. Dealer said the same thing about replacing the assembly (think I was quoted 1k?) Bought the ballast on eBay for 50 dollars. No problems since then.
Edit: 4G0907697G was the number I used to search it on ebay
157k on my '15. Had the DRL issue as above, and the master window switch on the drivers door broke, replaced that with a used one for ~8 dollars. Otherwise routine maintenance.