@Mary348
Hi Mary ....
To amend a booking and increase the accommodation charge. Go to their reservation and click on Change/Cancel. Choose change. Here you will see a page with a break down of charges/dates, etc. In the accommodation box add on the agreed extra cost to the existing total. This should include the total additional per person/per night and you can also add on any agreed additonal cleaning charge. You send this to the guest - who must accept it - if they don;t you only receive the original amount.
So assuming you have agreed this with the guest, and they accept the booking change, then you will get paid the extra.
Security deposit: do a search in the community centre on security deposit. There are lots of great articles and guides. In brief, the security deposit is not charged to guests it is an agreement by them to pay up to a certain amount in the event of damage (not wear and tear) which they agree responsiblity for and AirBnB agree is reasonable too. You raise a claim within 48 hours of the guest departing usually via the resolution centre if necessary (ie you and the guest disagree on the damage or amount). You may find that a guest agrees and is happy to pay you any damages via AirBnB - which means less hassle.
Cleaning- all charges for cleaning should go through AirBnB, but I can understand if they wanted to pay your cleaners direct and that would be fine I think.