@Hayk5 You're going to need to take this to Twitter with a direct message to AirbnbHelp. Get a signed and notarized statement from the plumbing person stating the plumbing was tamper with, not once but twice. Also provide the receipt and document her request for more A/C which you provided instantly with her threat to cancel if you did not provide it, it was not a listed amenity this is extortion. Have them check her prior stays for similar refund demands from other hosts. Demand that this case gets escalated as the guest commited fruad to get refunded and you demand the Trust and Safety people be brought in immediately to investigate this situation. You must use the word INVESTIGATE that is so important in getting results that work for you. Can you open a case you get nothing, can you please check on why this happen you get nothing. An investigation means issues and the guest need to be investigated, they can not deny them with your plumbers notized statement or your documentation on the extortion of install more A/C or she cancels. There were two cases of something similar to this recently on Reddit or Airhosts Forum in the last few months or so and both got their money back, but it seems it was AirBnB that actually paid not the guest. The guest walked away scott free, but their accounts were cancelled.