It's easy for all us folks on the sidelines to be tough and demand all sorts of things, but reality will probably tend to be a little different. In other words, don't let any comments about lifetime free maintenance, total engine replacement, kissing your posterior daily for the next millennium, stringing the offending "tech" up in the middle of the shop by his gonads, and all that other stuff go to your head.
First, insist on talking to the Service Manager or the Parts and Service Director, not one of the service writers. Calmly state the facts as you perceive them, let him or her know what you consider to be a proper and fair resolution to the problem, and listen to their response. At that point, if you don't like what you're hearing, insist on talking to the dealership General Manager or the Dealer Principal (some dealer's aren't directly involved and have a general manager handle everything). You can also file a complaint with the manufacturer, even though it isn't a warranty issue, to see if they would like to offer assistance toward a resolution. It never hurts to ask.
Jerry