Now, the Front Desk agent who said "no problem, I'll change it for you" will get an earful from Revenue Management when they see that I've worked both sides of that equation and there are two different mindsets at work. The FDA just goes into the reservation and changes the number of days or dates and clicks through, ignoring any boxes about rate changes. In Revenue Management and in-house reservations, we ALWAYS re-shopped the rate and that was what you would now be charged for adding/deleting/shifting a stay. Monday mornings I hear plenty of swearing in Revenue Management over things that Front Desk did over the weekend.

You lucked out this time. But, you were correct to contact the hotel directly. Since it is their bottom line, they will be the the ones who feel the loss/gain of that action.