There's a few things you can do. Get a parts cost from the dealer (they will be the highest for most things), and look up the labor time on Mitchell or Alldata. Multiply the labor rate by hours, and add parts in. That should get you in the ballpark. $700 is astronomical. If there is management higher than him I'd consult them, and also file a claim with the Better Business Bureau. The diagnostics couldn't have been too bad to do, although I've had some that made me want to tear my hair out.

Hate to break it to you, but a lot of shops charge more for parts than what you can buy them for. Let's say a sensor is $49.99 at Autozone. The shop has an Autozone Commercial account, and can get the same part for $25. They then mark the part up to $89.99 in order to hit their gross margin percentage (usually 80% at most shops). When I was service writing at a shop I would have to mark parts up 4-6x what we paid just to hit numbers. It's not fun for anyone except the big bosses who collect. The worst one I had to do was mark up a $350 part (our cost) to $1,600 to hit numbers. Can't remember what it was for sure, I do know it was a dealer-only part.