There are many companies you can use for discount hotel and vacations homes booking. Several have failed me or failed friends. The one I have always had wonderful experiences with is Expedia, and their subsidiary, Vrbo.
Vacation homes through Vrbo typically partner with a local agency. As an example, a Hill Country Vrbo booking puts us in contact with a local agency in Fredericksburg called Gasthaus. We deal directly with them if we have any questions or concerns.