Airbnb's trip extension system is broken and creates bad will with guest
The system Airbnb uses for trip alterations is really poorly implemented.
Essentially, in the background, it cancels the reservation and re-creates a new one. The problem is if you're using dynamic pricing that has changed the pricing of the already booked dates since the booking, it re-creates a new price for the entire stay based on those lower rates.
6 months ago a guest booked 5 nights for $300/nt = $1500 total
1 week before their stay, guest wants to extend their stay to 7 nights. But now since it's so close to those dates, your dynamic pricing has updated the price to $240/nt.
Instead of Airbnb adding $240x2 = $480 and charging the guest $480 for the 2 additional nights, it now recalculates the entire stay as... $240 x 7 nights = $1680, and the guest has already paid $1500 so if they put in an extension request Airbnb will charge them $180 total ($90/nt) for 2 additional nights if I accept it.
Of course, I have the option to deny it and offer it to them at another price but that creates bad will with the customer, who thinks they are being bait and switched. Which is exactly the scenario I have going on right now, with an upset guest that thinks I am trying to pull a fast one on them because of Airbnb's really poor system for handling this.
Airbnb does not cancel a reservation and creates a new one when changing a reservation. The reservationnumber will be the same.
This problem can easily be resolved: you as the host has to use the "change" option on the reservation. After setting the right dates the system calculates new price. Then click in the Price Field and enter the correct total price.Then sent extension request to the guest.
Right, ideally the guest would make a request via messages, and then I could set the price. But the guest also has the option to submit the alteration request directly without ever talking to me, which is what they did in this case. Now as I try and explain the situation to them, they feel lied to and misled.
And with respect, you're wrong about the canceling and re-booking. Even if that's not physically what they're doing, that's how they're determining the price, for some completely irrational reason, as if the entire booking were being re-booked at current prices (which might have changed) rather than just the new dates being booked.
If a guest has a booking from Dec 1 - Dec 4 and they want to add two days, Airbnb looks at what the price would be for Dec 1 - Dec 6 at current rates and then subtracts out what they've already paid to come up with the difference they owe. Instead of just looking what booking Dec 5- Dec 6 would cost and adding that.