You're travelling on your own for the government and you found a way to save money but you're subject to the Joint Travel Regulations as well as the Federal Travel Regulation. What do you do?
You went ahead and saved the government money and were proud of yourself. Unfortunately, your finance office stiffed you when it came time for payment. Its time to learn about rules that are mandatory.
See the case at cbca.gsa.gov. (it is only 2 pages.)