Rocco accepted the reservation, but was not able to welcome us and asked us to cancel the reservation ourself.
However, according to Airbnb policy, this is the host responsability to cancel the reservation when he cannot welcome the guest, (otherwise the guest has to paid reservation fees). We asked Rocco several times to proceed, but he refused.
Conclusion: we had to find another solution in emergency, and to complain to Airbnb.
Thank you Rocco for this huge amount of wasted time...