Response from Alex:
I am sorry that Regula locked herself out of the flat, but the keys - as well as the other equipment of the flat - are on the responsibility of the guest during their stay. I was not even in Paris at this moment, but I spent all the afternoon on the phone to find someone to resolve the situation and with Regula until I made sure everything was out of order. She also insisted that I pay for this which I find out of the rules of airbnb. All my best regards.