It is great until you call back and get the same agent again.

Varies based on how far you are into a conversation and also if you're trying to get a favor/waiver or not. If there is a risk that the agent will document the reservation akin to "PAX informed XYZ not permitted" then you need to find a way to back out of the request before that happens. Once the record is notated getting past that is hard.

Also, don't be a schmuck. If you can work in something along the lines of, "Thanks for trying; I guess I need to think about my options and give ya'll a call back later," that is a polite way to "hang up" the call.