Originally Posted by mikew99

This is the important part. OP, check your email for the eTicket Itinerary and Receipt. It should have a section labelled "Baggage allowance and charges for this itinerary," under which you can find the 1st and 2nd bag charges, along with the applicable dimensions.

DOT rules state that airlines must give "correct, specific baggage allowance and fee information on e-ticket confirmations sufficient for consumers to determine the allowances and fees that apply to their travel, including travel on code-share and interline itineraries.... [T]he baggage allowances and fees that apply at the beginning of an itinerary must apply throughout...[and] must take into account the fees that apply to that itinerary."

If the above explanation doesn't yield results, then a DOT complaint should.