[al levy]

that was excessive however the way labor is figured whether it be an automobile or a boat is that the manufacture has a labor guide and the mechanics follow that. now there is also a full price labor and a warranty labor time. not the dollar amount but the hourly time .
not to necessarily take anyone's side but these labor guides don't always take into consideration broken, rusted, stripped etc. bolts.
if you note up until maybe 7-10 years ago you very rarely paid for diagnostic time and now almost all repair shops charge that.
you can also buy your own parts but then get into a pissing match with the mechanic as it was your part not his that failed.
As i had explained to me once and i thought it was very fair if the retail part that your mechanic just installed fails he is responsible for changing it under warranty. The reason he charges retail price is to protect his own labor if that part fails. very rarely will a manufacture pay time for replacement of that failed part only give you another part.
Word of mouth, someone with there doors open for more than 3 months (unless moved etc.) and a few phone calls to other repair facilities to verify price are all good ways to check price.
Again if you were quoted around 300 then where is the rest. stop or call any authorized merc dealer and they will tell you what the labor time is both warranty or retail. they will also tell you the suggested list price of those parts also whether it be a complete impeller kit or just the impeller and gasket.

[JRCustomCar]

A lot of jobs are billed by what the service manual says it should take for time. Most times, it doesn't take as long as the service manual calls for, but there are some times that you run into stubborn hardware and whatnot...I would say that it could be reasonable to pay for up to twice the "standard" service time...but I'm sorry that you ended up with something like that.

[JRCustomCar]

I missed the last post...Al's on point.