I have to go back to the dealer, and if I'm told that I need to buy the part, I will raise hell with Customer Care. I fail to see how these are warranty items. Their software is failing, it has never been tampered with, and its rejecting their software.
Person name/Date/Time:
What you asked
How they replied
etc.
I know it sounds silly but being charming is disarming, while the thought of being held accountable is so far counter to your demeanor that people err on the side of "better be safe than sorry". Dealerships are prone to trying to charge for things they know damn well they could get covered - having the documentation that they tried to "work" you means they might just stop being lazy for a few.