I did tech support for a startup a long time ago. I mostly won't do any phone support for friends and family because they have the nasty habit of doing something like this:
Me: What do you see?
Them: <click> <click> <click> Nothing.
Me: What are you doing?
Them: <click><click><click> Nothing.
So I've been doing it in person or don't do it at all. Too many hours trying to visualize what in the world might be on the other person's screen.
The reason I'm moved to comment is two things: one is that my daughter in college had me help her file her taxes by starting with FaceTime on her MacBook, then sharing the screen so that I could see exactly what she was doing. She's not technically inclined and it wasn't something that I suggested, she figured out how to do it herself.
The other thing is that my mother-in-law is 90 and also not a techie. But I've been able to help her with 1 or 2 issues remotely because she's able to take a photo of the situation with her cell phone and text it to me.
Things have progressed to the point where hopefully your customer could have been convinced to send you a picture and saved you a trip.