I had a similar situation with plumbing. I had raw sewage under a rental. I
had a company come out. They said the line was broken and they'd have to
dig it out and replace it all. I researched the whole thing. The sewer
pipe runs 14' underground. They told me it would be $8,000 or more to do
the job. It all seemed to "smell wrong". I called another company. They
looked and said that some plumber had connected the toilet wrong and raw
sewage was just dumping from the toilet. (So much for that plumber!) The
first company billed me over $400. I wrote them a nice letter. I said I
appreciated their response to my need, but that their assessment was
incorrect. That the problem was a pipe that had not been glued properly
under the toilet. That had their man actually gone under the house he
might have noticed that. That I would give them the money for a call out
but not $400+ for a wrong diagnosis. I sent a check and the letter and
never heard another word. I'm sure were I to call they'd probably not
come, but I'd never call them.

I'd suggest a nice note. Telling the first guy that you had much more
significant problems than just the "dellee-bobber" and that an experienced
electrican friend came by and helped you out. That the whole job is now
completed and has passed inspection. Thank him and enclose a fair amount
via check. He can return any purchase and shopping, if he's a pro, should
be easy. (He should know what company carries what he needs and he should
know where the items are he needs.) He didn't have to actually install
anything and he'll get something. I'd estimate shopping time at 90
minutes and pay accordingly. (That should cover his travel time to the
store, too.) So I'd probably give him $99. What took five hours? If it
really took that long, I'd begrudgingly pay it. At least you saved the
rest. He's saying it took over FIVE hours to purchase parts. Maybe call a
company and check how available what he purchased is. And if he's
including parts, I'd make him take them back. If you have a contract with
him, you will owe him a fair amount; but things happen. I've had this come
up for me. I wish I had the job, but someone else will do it for less. I
bill my time and move on. I've only had one person stiff me and not pay
anything when we have a contract.

Explain that the check is for payment in full on invoice #123 (write on the
check, too.) and that should be that, especially if he cashes the check. It
is amazing what nerve some people have. They think that they can bill
ANYTHING. It takes a lot of hours for me to make that kind of money, so
seeing it go out for so little is urksome. Good luck.

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KaCe