[jcslocum]

If you now have the car and paid by credit card, you have leverage to discuss the total of the invoice with him. An "extra" $1300 in overage isn't reasonable from the estimate if no extra work was done or parts used. Go back to him and assert yourself. It's not personal, just business. The worst that can happen is he will refuse to work with you on the bill. That is exactly where you are now, so nothing ventured, nothing gained (recovered) by you. Yu don;t have to go nuts or be come an AH, just state your case and demand a refund.