Hey David, after reading your first post it brought back many memories of dealer nightmares, and I just found a nail in my tire last night.
Just a few facts on tires and repair kits using plugs. I have one in my vechicle, but its used as a last resort in an emergency. Yes they will out last the tire and get you home. As of a couple years ago they were not approved repairs in a few states. I do not know why though. It might have changed since then.
Why are they not the suggested repair method? Lets dissect your tire, removing the rubber, underneath you have the steel radials that line the tire. This is like a steel gauze or mesh. This is what provides the structure of the tire and weight ratings, cornering abilities, etc. When you repair your tire, lets say pulling out that nail or screw that we have all gotten at one time our another. Then compare it to the folded leather plug. Its much thicker than the nail/ screw, resulting in steel radials getting disturbed. This results in a very annoying noise in the tire. Like a whomp, whomp, whomp, etc.
Like I said, I have a kit in my vechicle, for emergency use. Nails in the center section of the tire can be repaired using a patch. The outside threads cannot be repaired by a patch resulting in you buying a new tire, so that I would plug.
Just some food for thought. To the other part of your post, I feel your pain. I had my LR4 @ the dealer and recieved a door ding while it was there. I was so ******. They removed the ding and gave me $350. to have the small scratch fixed, which I did myself.
I would take the free detail. Why not? Their body shop will probally do it, or it will go to an outside company that they use for proffesional detailing.
Frank