When Vendors don't answer calls, emails, voicemails?

I won't buy from a place that doesn't at least return calls or emails either.
The Wife and I own/operate a computer service business, and people would be shocked at how many customers think we are their personal tech support via phone after they have paid us for services.
It's like some people think once they have given you money for a service everything they want after that should be free.

We have a system after a couple of decades.
I NEVER answer the phone, because people want to get free help with emailing a picture (or whatever).
The Wife answers the phone.
If she can't help them (and she does her best to try) then they need a paid appointment with me for picture emailing training. (or whatever)
They only see me when I am getting paid for it.

We have actually gotten calls asking if we know someone that will do onsite service cheaper than us.:rofl:
I got called over by one of my sales girls the other day. She had a guy on hold and told me " this guy says he isnt buying our engine, because he can have it done cheaper, BUT he wants me to tell him what source and part number we use for XYZ so he can quote "build the exact same motor" ....
I understand some people have no shame, but you still have to be polite, as RIDUCULOUS as his request was.

I told her to tell him we manufacture many of our own parts, and for proprietary reasons we don't always have common part numbers (which is true) told her to send him to me if there was anything else he wanted. He hung up.

In the words of Patric Swayze...
"Be Nice! if they wont walk, you walk them...but Be nice" LOL

Still have to be Diligent and polite...tough as it may be