Not had many bad experiences but a certain Peugeot dealer (who shall remain anonymous) reflashed, as a matter of course, the ECU in my car during a routine service. Thus overwriting my custom ECU map. Not just fuelling and boost parameters but pedal response curve and something that I had one specifically to allow me to use cruise control in 3rd gear as well as fourth and fifth.
Thankfully Celtic Tuning sorted it out for me for a few dozen quid so thumbs up to Celtic in North Cornwall.
I was also disappointed with a certain local BMW/Merc Specialist (no names) who fitted a new water pump and left a failed bleed screw in the expansion tank. Lost coolant - thankfully I noticed soon enough and sorted it out. New screw - 35 pence!?!?!?
How ignorant.
The same 'specialist' also fitted front discs for me and within two weeks I had brake judder. Laziness on their part, the hubs had not been cleaned up and as a result I had pad material transferred unevenly to the front rotors thus introducing pedal and steering judder.
So I gave up, bought another set of discs and pads, handed them to Crendon Motors, Long Crendon, Bucks (whom I very HIGHLY recommend indeed) who did the job properly.
That front set lasted 30,000 plus miles, the rears are still on there and there is not juddery shuddery stuff at all!!!!!
It's hard to know who to trust but these guys (Crendon Motors) are good.... patient, knowledgable, experienced and the pricing is not remotely outrageous either. Friendly and personable too - can't argue with their business acumen in the slightest.