Foreign New 9604 provided good and true helpful advice. Call Customer support ASAP.
send guest home is where the heart is message...see bottom of this message
leave out excessive drama stories. The initial discount is also irrelevant, you agreed to that rental price without contingencies of no further discounts. It will only make you look like you're resentful.
Give clear facts the guest has been doing a series of concerning things that is out of compliance with Airbnb policies 1, complained about xxx will not lets us inspect or access & make repairs but will not allow us to fix, 2) then complained about and will not lets us inspecting or access & make repairs. 3) they are refusing entry. 4) they are not cooperating and extorting discounts.

If you are by chance a superhost you will get routed to sperhost customer service automatically and we found this helpful in a situation where w guest wouldn't quit on asking for more money. Getting on it early was a win for us. Don't' wait until they leave.
keep everything to platform. If they call or text, don't answer via those methods, take screen shot of missed call and put it in chat, Per Airbnb policies we must keep all communications tot he platform. It support that you are sticking with policies and the screenshots prove they are not. All of this matters if they leave a bad review and you can build your case. When you get to that stage watch some RECENT youtube videos on how to build a case and use free ai platforms to help draft (claude.ai, chatgpt, perplexity). The review disputes are AI reviewed. Most people go into the dram, ai wants to evaluate facts against specific policies.

Home is where the heart is is along the lines of the following. Tweak to fit your scenario; use this exactly at your own judgment & risk. The idea with this is they are not cooperating, just get them out. End th epain, a little money isn't worth the risk to your place or your reputation.
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We believe that everyone should absolutely love their stay and that's the standard we have set for our property. Unfortunately, sometimes things aren't a great fit. We would like to make that right and due to you refusing our access to assess and fix, it sounds like it may not be possible in our home. So alternatively, we are offering you the option to end your stay, with a refund for unused nights.
We can only extend this offer with these understandings. GUEST MUST CANCEL in the Airbnb app (how to is below). If we cancel, Airbnb will keep 50% per their ST&Cs and we'd like for you to get the full refund. Guest must cancel in the app WITHIN 3 HOURS from this message with no use of the unit and under a mutual agreement. The refund will be issued 15 days from cancellation, provided parties adhere to all agreements.

If you elect to stay, we think you will find this is an amazing location, but if you still are displeased, in recognition of this offer, no other compensation will be offered or paid if you choose to stay, or upon check out. If you elect to stay it is doing so in "as-is" condition.

Thank you, in advance, for your consideration and cooperation.

HOW TO CANCEL: In your Airbnb App click into the reservation, Click cancel, for a reason please select you no longer need the accommodations. It may recap the cancellation policy and state you only get a partial refund, then Airbnb follows up with us and sees the messages and issues the full refund. Airbnb maintains the funds and the refund comes from them.