call your state's BAR - Bureau of Automotive Repair and report them. make sure you have your receipts and all documentation.
Hate to say this, but take your car somewhere else instead, get it diagnosed, in writing, then have it repaired.
I would also consider taking the first shop to small claims court. don't try to get the whole bill compensated, but just the excess part.
Also, goto your local library, and find the Mitchell estimating guide. they should be in there, otherwise, goto another library.
in the Mitchell book you will find your car, and a whole slew of services with hours attached to them.
the mechanic is not allowed to go beyond what that estimating guide says in terms of hours.
So let's say to replace your water pump, the book says 1.5 hours. the mechanic can charge you 1.5 hours times his labor rate.
Now, there are also subnotes to that, like for instance, remove belt, .2, remove power steering pump .4.
That's now 1.5 + .6 hr, so 2.1 hours total.
A shop wants a tech to beat that time as stated in the mitchell book because they'll make more money by getting the car done faster. if it takes the mechanic longer, the shop loses money because they are not supposed to charge you more time for their slowness.
Now that 2.1 hours, can be "fudged", so they could add an extra .5 hours to the total, and that'd be considered OK.
Also, calling the BBB, is a waste of time, they do nothing to help you, they simply put a bad mark on the business, nothing happens.
the BAR will help you, they will go and audit the shop and the shop will be very sorry for them coming in. the BAR can take away their license to do business.
It could take the BAR a couple months to get to it, but believe me, here in California, shops quiver in fear when the BAR comes around.
Also.. very important.. if you are able, I hope you paid with a credit card, this gives you fighting power against the shop. a check can get cashed quickly, cash gives you no paper trail and DEBIT gives no fighting ability either.
the card company will make the shop justify the charges.
I had to fight american express one time, I won, because I followed the mitchell manual estimating times exactly, the argument was the labor rate, the customer saw the price for a smog inspection and though that was the hourly rate. But I had to jump through hoops to win even though I was right.