You might be able to get this done at the airport, or if there is someone you know that you can call. But if you just call res "off the street" I am 99% sure they will not do it. Regardless of what airline we are talking about, the airport has a lot more discretion and latitude than reservations call centers. Going to the airport is no guarantee either. Another thing you might try is just show up a day early or whatever you are trying to do and see if they will let you go.

One thing you should be aware of that people often forget about is that if you do call or go in, and you are denied your request, they may annotate that in your record and then you will have a good deal of difficulty quite possibly if you just show up early.