I can't believe I read that entire thread. LOL
yeah, i say to let this go.
Seriously I can not say that this is the RC shop's fault, ..nor yours either. Seems like too stubborn people butting heads to me. The hobby shop could have been cool and let you exchange them at first, ...but I am guessing that lady was told to not except exchanges once they've been opened. She was just trying to do her job ...overzealously but still.
It's not like you can't use the tires rights? (I have about 20 sets of tires for various applications and vehicles ...I can always use more).
anyway, don't stress out over stuff like this. Life is waaaay too short.