Good points, sggolf, but I still believe that the travel agency is responsible for knowing the different tarriff rules. They acted as my agent and should have advised me not to book that way. I simply asked the question. They booked the ticket. The obviously agreed with me as the issued a credit in full. As far as the amount of tickets they must sell, since they're hitting me with a $20 fee with every flight booking, it eases their burden for THEIR mistake.

In the future, if I found the need to take the risk, I would certainly use different airlines. . . and probably book them myself (don't thing the travel agent would eat another fee.)