I think both Trvaelocity and Expedia are equally bad. Their systems to do not address complicated situations and the customer service is almost non existant. Next, these services will have a "trusted" credit card user.

Recently, ( from US) I tried to buy a RT on SIN-BOM on Expedia. The loaded fares were old and the only way they could terminate the transaction was by telling me that Discover had denied the charge. Discover told me that the error was at Expedia's end. They locked out the Discover Card account # and no one at Expedia cared to address the situation.

BTW, I did buy the ticket without any problems on Travelocity! Go Figure!