Doesn't imply OEM on the receipt. I got a plumber to fit a new bathroom, found out he was using plastic pipework but I never specially asked him if he was using copper so he fitted what he wanted.
On Alfa Romeo I got a very well well known specialist to service my car, they took me big time for a whole set of brakes, the invoice was eye watering but I never went back. I bought a 156 and the last receipt again from a well know specialist was for a fraction under £1000 for a service and front disks and pads. Another well known specialist changed my cambelt, I collected the car in the dark, it was parked very close to something up front, later I found significant damage to the front bumper, could never prove it was them but I never went back there again either. A mate at work recounted a story when his wheels nearly fell off following a service, luckily the banging got so bad he stopped. In my experience you can almost never trust anyone to do a good job, the list of poor experiences I have is endless.
Alfa Romeo GTV T-Spark