Sort of a reverse horror story here.
A few years ago I bought a new Specialized Enduro mtb from a well established LBS. All great until I took it back there at the end of the season for a routine "Gold level" service. When I got it back, first thing I noticed was that the new dropper post cable was too short and the seat wouldn't latch in the upper position and wasn't long enough to adjust correctly. So after they fitted another new cable I took it out for a ride. After a couple of miles the drive side crank came loose and all the cable clamps on the downtube started falling off. While I was re-fitting the clamps I then noticed that the rear shock had been re-fitted upside down and the air valve was digging into my frame close to full travel. All said it was the biggest **** show I've ever seen from a bike service. Funnily enough I haven't bought anything from that LBS again.