With not being able to get any detailed information from him you should have at least asked for your old parts since they are yours and I'm sure neither one of them required a core so he couldn't use that excuse. If he had hesitated there then you would know he didn't replace them.
Somethings that might tell you that he didn't replace your fuel pump.
Do you recall if your car had the same amount of gasoline as when you had it towed there. One of the steps in replacing a fuel pump is to remove as much gas from the tank as possible.
He would have had to remove your battery. Did you have to put in your radio code to get it working again?
I'm sure there are plenty of other tell-tale signs or things you could check but I think these two would be certain give-aways.
Here is a link to replacement of a Boxster fuel pump so maybe you can look and see if there appears to be any signs of work around this area.
After I lost my usual place I would take my car I looked around and found
this shop. It was a bit of a drive but I was impressed with their service and the owners time and ability to clearly explain to me what was wrong with my car and what they did.