Always get a written estimate for parts and labors. Make sure the estimate states that the shop will contact you for approval before performing any work exceeding a specified amount of time or money. When you pick up your car, ask the service manager to explain all work completed and all replacements made. Also get a completed repair order describing the work done. It should list each repair, parts supplied, the cost of each part, labor charges, and the vehicle's odometer reading when you brought the vehicle in as well as when the repair order was completed. Ask for all replaced parts. Also, ask that any major new parts that have been installed be pointed out to you, if possible. If the shop guarantees its work, get the guarantee in writing.