As a general process, when a connection becomes unviable, usually the robotics suggest an alternative, it's not immediate it can take 15 minutes to become apparent, and the App's cache may need to be refreshed. Sometime the robotics can't do anything, for example because it's a 001 AA ticket rather than 125. Initially the robotics don't consider MCT, that is a separate robotic that may only operate some days later - so no good here. For simple bookings this all works fine, bookings with connections can get mangled so that's when to talk to an agent. If you are sticking to the booked route, the agent will be able to move to any service, though the rules / policy is -2 days to +3 days if it's delays, more generous for cancellations. Many agents won't know that, so usually they will do whatever you suggest.