Hi @Claudia1162
I am sorry to hear this but why on earth did you wait until the guests had stayed to review the security cameras. It is quite common for guests to lie about numbers to save money/book a place with lower numbers.
You should have reviewed the CCTV on check in or at least during the stay. Then you could have told the guest you would cancel the booking as he had exceeded the numbers booked by over 100%.
If you have it in your house rules that you charge for excess water usage over XXX amount you can try putting in a claim.
Similarly if you can show there was extra cleaning, submit a bill from the cleaning company.
If you have a property that is suitable for parties, you do need to be able to monitor it more carefully to make sure people don't abuse it and have comprehensive house rules in place about sanctions if guests come in who haven't booked and paid.
I do hope you have left an honest review so that hosts know about this dishonest guest.