I bilieve this is a community message board. Your message seems to be directed to Airbnb specifically.
As a fellow host I´d recommend not accepting any another reservations until your cleaning fee error is corrected.
For the 2 reservations you aleady have I´d ask for the 15€ directly to the guests upon check-in. If they are recurring Airbnb guests they will understand as cleaning fee is almost always charged and if they are new guests then they will find out about the cleaning fee.