I submitted feedback as if it was a bug. Airbnb claims they don't respond to bug reports like normal support tickets. So I suppose time will tell... or maybe somone will answer and say it's setup this way on purpose...
Copy/Paste of the Bug Report:
<quote>
The alteration tool has a glitch. During the creation of the alteration request, the website does not refresh when the user manually changes the fee. For example, if I begin an alteration request for Guest 1 to change him from listing A to listing B, the platform automatically calculates the new rate based on the pricing settings in Listing B and calculates the difference in costs for Guest 1. However, when the user manually overrides the cost (perhaps to insert a negotiated price or to match the price of a comparable listing or even to incentivize a longer stay or to change rooms because an existing guest wants to extend), the cost difference does not update visually.
Furthermore, when Guest 1 receives the request by host for alteration, the guest is informed of an additional charge. However, in one example, it appears the guest was not charged this additional fee.
For a live case study, please review the transaction between myself and Robert ******. This guest booked a room that was being vacated in my home by Bahig ****. After realizing Bahig had not vacated the room, I touched base with him and he expressed his desire to rebook for an extended stay. I explained the situation to Robert and obtained his consent to alter the reservation. I submitted the request. My version of the alteration showed $0 change in rate, even though the "difference" column still showed the difference between the published price of the listing and the original listing he booked.
When Guest (Robert) went to confirm the alteration, the airbnb platform indicated he would be charged $14. He booked anyway. I checked with him today and it appears he has not been charged.
Instant book has created some headaches and challenges. I believe a functioning Alteration tool will empower guests and hosts to resolve many issues without the need for Airbnb intervention. I'm happy to provide more specifics, screenshots, or details to assist in correcting this bug.
Many thanks! And cheers to 5 star hosting!
David **
[phone number removed]
</quote>