I have managed auto repair facilities for almost twenty years. Even if someone tells me " Just fix it, I don't care what it costs." I always call and tell them the estimate before I begin work on the vehicle. I checked on Alldata, and the fuel pump calls for 2.2 hours. My shop here in Minnesota charges $99.00 / hour. Add diagnostics of $99.00, the part at $280.00, and assuming a $100.00 tow, that comes to $696.00. That's alot of money, because I know we are not cheap, just really good. $900.00 is way out of line. In Minnesota, we cannot hold a vehicle if the customer demands it. Even if he refuses to pay, we have to release the vehicle, because it belongs to the owner, not us. If we want satisfaction on the bill, we have to take the owner to court to collect. This has never happened to me, but I know of it happening. Check the laws in your state. Also, you can dispute the charge with your credit card company, or stop payment on a check. Make them prove that their charges are valid. i don't believe they are.