Hi Esther,
I wish I had an easy answer for you. Unfortunately, the whole review process is geared towards the guest and NOT the hosts and there is almost nothing you can do.
For example, we had one guest stay at our place. Police were called by a multiple neighbours because she was under the influence of drugs and causing issues in the street. Police attended and she was issued a warning (all unbeknown to us as we don't live in the same town). She left a horrible review which had nothing to do with the house but about her interaction with the police and in doing so, dragged down our whole rating.
When we approached AirBNB (with the police report) to say how unfair this was, they said they would not remove the review even though it had absolutely nothing to do with the house.
Until AirBNB decides to support hosts more, you'll likely encounter a number of unfair instances which threatens the success of your property.