Re: P20EE possible on brand new vehicle?
Based on what I know about the cause of the P20EE error, it's extremely unlikely that was the MIL when the car was brand new. I believe it takes several thousand miles before the effects of too much DEF injection causes the cat to go bad. Salesman #1 may have been telling the truth (that was hard to type!)
The first reaction to the P20EE error is indeed to update the software which, among other things, decreases the amount of DEF injected. When it comes back, the next step is to replace the cat. Except for the trips to the dealer, it's a relatively easy problem to solve.
Good luck, push for a new cat whichever dealer you end up going to.