hello @Ines61 , looks like you are brand new to hosting and these will be your first guests. congratulations, you have a great listing.
As it is, you're best off to just let this stay happen as it is: it seems too late to now ask the guests for more money. You can always look in "Reservations" and ask the guest from there to pay a higher price, explaining the mistake. You need to use the "change reservation" option and ask for more money. The guest has 24 hours to accept, otherwise it stays as it is. I doubt any guest would just accept a higher price, so I would leave it alone.
But for the future: make sure your calendar shows the prices you want to charge. I looked at it, you have instant booking on- you might not want to do that at the very beginning. Practically all July is blocked out, as well as almost all of August. either you blocked it out or you have lots of reservations. Make sure you understand all that.
when i click on something in August, it comes back with an average price of $77US per night, later in October it drops down to $47US per night.
Perhaps you also had "smart pricing "on, which is a price Airbnb suggests: that is usually very low and most of us hosts do not use it. You might have inadvertendly checked that.
Anyways, learn and study all the rules, also how pricing works, and you will enjoy hosting.
Good luck!
