Any suggestions on what I should have said or done? Anyone?
The only way to save your dignity would be to walk away.
If you told the customer that the wire is insufficient and not installed properly you risk:
A) Getting into a pissing match with sparkie (after all he does have a license you know) and you don't know what you are talking about.
B) Having the customer tell you that you are only saying that because you didn't install it and sparkie was cheaper.
C) Having the customer accuse you of trying to make extra money by saying the wire has to be replaced.
D) And (drum roll) the customers IT guy said it should work fine.
-Hal