The theory of dealing with these matters is always easier in 20/20 hindsight. The reality can be different.
I have a relationship with this garage of many years, although as I said there have been some changes of late. They have looked after up to four of my cars at a time, and there have been no previous issues whatsoever. It is fifteen miles away and for me an extremely uncomfortable drive, each way, twice.
The car was in for a service and MoT. At the time I was informed that there was a problem with the hub the MoT had expired. I would therefore have had to instruct them to finish the service, and then, having made another Mot appointment elsewhere immediately, taken my wife to the garage so that she could take the car directly to the new appointment.
I feel that by asking for the part I covered myself well enough, but of course I am disappointed that it was not supplied as requested. I will consider the situation further once I know if it is to be returned.
At this point I genuinely don't know whether everything is kosher, it may well be that everything is in order; what I do know is that for the sum involved legal action would be serious overkill.
Life is too short.