Originally Posted by
canadiancow
Why is Expedia an option in the dropdown on the DOT complaint form if DOT can't do anything?
Because there are other laws DOT do enforce which covers travel agencies such as code-share disclosure.
Regulation Z applies to Expedia but not 14 CFR Part 374. Easiest and quickest route is to dispute with credit card issuer. Try FTC if you want Regulation Z enforced against Expedia.