Sounds like their problem, not yours (other than the hassle). Is this a BMW Dealer or independent repair place?

They were in place before they took things apart, which they didn't need to do if they'd have bought the german auto specialties tool for valve seal repair...

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Kirk
Las Vegas
2016 X5 40e Mineral White/Black Dakota Leather, ZLL, ZCW, ZDA, ZDB, ZPP, multi contour seats, rear side window shades, HK stereo
2011 E90M3, 6-speed manual