Hotels and airlines charge you a fee for altering your travel dates. This helps offset revenue lost from last-minute vacancies, as well as income lost to lower, closer-to-the-date pricing.
We ought to have an option to charge an alteration or change fee, either a fixed rate like $200 or a variable rate based on the average cost per night, like "as per the host's policy, you will be charged a fee equal to one night's stay if this alteration request is accepted."
I had a regular guest book an entire month, 5 months out. A few weeks before her arrival, she sent an alteration request saying she wants to stay just two weeks in a totally different month instead. I'm doubly screwed: 1) anyone else who wanted to book those dates in the last few months saw that they were blocked. 2) Even if I get another booking, the rates are lower because it's much closer to those dates.
If I say no to the alteration request, I lose a repeat customer and I get a bad review. (And maybe she cancels her credit card to avoid the cancellation charges and I don't even get paid.) That's not an option. I have to say yes.
Since there's no fee involved, she can do this as much as she wants. In fact, after I accepted her alteration request, I got another one a few days later saying she wanted to shorten her stay to 6 days, and she totally changed the dates again.
There ought to be a penalty to discourage this kind of behavior, and to offset host losses in the event of an alteration request.