That's a great suggestion! Mendoza was on my list of places to visit. If the cancellation sticks, do you think I could ask for IAH-EZE-SCL or IAH-EZE-MDZ? And any suggestions regarding when I should call? It seemed that the OP didn't have much luck with the agent and UA doesn't seem to have a plan right now, so I was thinking to give it a couple of days...

Like the OP, I also booked in PE, and would rather be in PE to SCL or somewhere relatively close to SCL like EZE, instead of needing to connect in BOG or LIM.