@George32
Depends - was the payment sent to an active account held by someone else. If so, they probably have received the money as you gave (for example) a correct bank account. In many countries there is little or no way to guarantee you get your money back as you made a mistake and the bank/agency/AirBnb is not liable for that.
If it went to an account that is closed/dormant etc (ie that is not in use) then you will probably find it has bounced back to AirBnB.
Contact them on Twitter and ask them to check - if they have it they can resend it to your new, accurate account details