@JennieLee0
If they stayed a month and depending on the size of the place, I'd think it isn't practical to take a back to back booking. You might have blocked a day out in advance, if it were possible.
You can consider as some ideas; restricting guests length of stay to prevent long term clients , perhaps charging a higher cleaning fee, to be part refunded on departure after inspection as an incentive. Mandatory weekly cleaning service for longer term bookings (for a fee) , no monthly discount fee ( you have 10 per cent off for example as a discount in one of your five listings.) No point in a discount if you are losing money post visit. All this is retrospective of course, so unless you have ongoing issues with your guests culture then maybe to put it down as a one off lesson learned.
Keep in mind airbnb isn't a flexible enough platform for setting conditions for long term bookings.
As far as gettting the resolution centre involved, airbnb often see it as a 'dispute' between guest and host, and it's easy for them to file it as too bad, cost of business, jog on. However, one of the booking conditions is -
11.1 As a Guest, you are responsible for leaving the Accommodation (including any personal or other property located at the Accommodation) in the condition it was in when you arrived.