Cancel a reservation without penalty once the check-in has already been done?

[Antonella612]

Hello,

I already asked to Airbnb Assistance but I've not yet received a reply, so I also try here because I have a problem with current guests.

Two night ago guests arrived but from the day of their arrival there is no current water in the house in the evening. Technicians have come twice but they can't locate the damage and still cannot solve the problem.

Guests ask for a total refund of the reservation, so both the money I've already received in my bank account, and also Airbnb commissions fees (110 EUR/131 USD).

Is it possible to cancel the reservation without penalty once the check-in has already been done?

Beside this Airbnb payment-related question, what if they ask me also for the difference in price to book another property near mine?

Thank you very much.

[Antonella612]

This morning I went to the house again (26 miles away from where I live) to talk with the guests about the problem and making myself available to wait the new arrive of the technician.

Guests didn't let me in, saying they would have wait themselves and for the moment not talking again about moving to another property or for a refund.

I don't know if they will stay till the end of the reservation, but I would like to know how to deal if at the end of the stay they will ask me for a partial refund. Price per night is yet the lowest in the nearby, for a full independent house and garden where there is nobody else. 

Which percentage of refund would you apply for low/no water in the evening hours?