Although I haven't made a transit like that through EZE I'm pretty sure you'll have to go through passport control, get your luggage, and go through customs. The only transit passengers that I've seen avoid that are those who are going to another country, others on this forum probably have direct experience to confirm or deny my assertion. There are no priority lines at EZE for any of this. 2 hours should be enough time but its possible that you'll miss your connection because sometimes it takes 60-90 minutes to get through customs and the line to check your bags with AR can be very slow too. There are multiple flights to Mendoza daily, so if you miss your connection you'll probably still be able to get there the same day. The VIP service doesn't sound like a good deal to me nor any of the other frequent flyers down here who I've spoken to. It would only be worthwhile for your situation if they could cut the lines at customs, baggage check, and security to re-enter the terminal, before you buy ask their sales reps whether or not that is the case (and share their response here please).