@Kath-Gay0 There are penalties for hosts cancelling a reservation which are clearly explained in the information for hosts on the Airbnb site. You should have either gotten the guest to cancel if they were still within the 48 hour refund window, then rebook when you got the pricing correctly set, or sent them a special offer to adjust the price.
And you shoukdn't have your calendar open beyond dates you have set the pricing correctly if you use Instant Book.
It's not very professional or ethical to expect guests to pay more because the host was disorganized with their calendar or pricing.
Contact Airbnb again, and explain again- ask them to look at the messages with your guest to see that it's a mutually agreed upon new price and that that same guest still wants to book those dates.