@Manuel7097
Sorry this happened to you.
This practice of automatically rewarding guests has nothing to do with Aircover, although Aircover is an equally deceptive programme.
We had a guest do something similar. If they don't win with the first complaint, they just make up another, and when that doesn't work, make up another... Until one of them works. You need to avoid attracting these types.
Did the guest just stay one night? It may be a blessing in disguise. And expensive one, but who knows what other imaginary atrocities you could have committed in the mean time? And how much would that cost?
Sigh. Pick yourself up, dust yourself off, and get back on the horse. But this time, screen your guests before they book. Seriously. And make sure they have nothing to complain about. Or dream up. And take timestamped photos just before they arrive.
Good luck.