If you know there is a bit back look up to where it’s coming from and take a picture and post it up, if you can see the oil then it only flows downwards generally so have a look at the highest point and that’s your leak
If it’s the under tray your seeing the oil on it’s a reasonable leak, but work put where it’s furthest point forward or the highest point it’s coming from, and then get under and look up
Could even be the sump plug!
There will be a drop off the sump or a low point normally... it’s not rocket science finding an oil leak especially if you’ve cleaned it off well
Before slating garages boys remember that to steam clean an engine if its lathered you can’t do it in the street or even a car park otherwise you risk prosecution, so it may well be that the garage didn’t have the time or facility’s to clean the engine off properly and weren’t willing to charge the customer for a half arsed job which is the right way to be with a customer regardless
As for other garages having ‘no business’ around the back of an engine... anything that requires the front plastic under shield being taken off will let them see a drop of oil or even without taking it off as it may well have been dripping off and a nice clean workshop will show it up if they were just doing a tyre, so don’t talk about stuff you obviously haven’t encountered previously if you haven’t got a clue how decent mechanics actually work and try to be helpful, the internet is great for slating people when in reality it was good that they mentioned he had an oil leak in the first place
