My brother works in the travel software industry (for a big player) and that market is an extremely hard nut to crack, unless you are coming at it with a boat load of contacts and money.

The big tour operators (I know this from the European side) are quite well tied into the bug boys contractually. They often will enforce sole-usage on hotels to prevent this kind of side market entry your parents have attempted. the hotels can be penalized or dropped from the operator's books, for simply offering rooms outside the tour operator.