recruit an airline ally
Today I gave Jane my advice for rearranging flights. Recruit the operator to be your ally - "Hi, I need to get home as soon as possible, and I'm broke. Can you help me save money and travel sooner?" Present the larger problem, instead of focusing on the cost or fare class of this or that ticket, this or that routing. They have the computer and the knowledge of the system, you have need for their help.
The second piece of advice, if you get an operator who is not being helpful, thank them for their time, wait a few minutes, and call back to see if you find someone more sympatico. If you're so broke that $150 is a big deal to pay to change a ticket, then it's worth it to spend an hour trying to save that money. If you have a good story to tell, or an odd flight routing strategy to test, often its just a matter of finding an airline operator who will be sympathetic or excited to participate in that with you. Unfortunately for Jane, I've found that I can bond better with operators in the United States, better than I get along with phone operators in Japan. But she is much more polite than I and that should serve, if she can manage to work a bit of self-interest into her language.