Illegitimate Security Deposit Demanded.
The Hotel 3 hours prior to stay demanded a hidden, illegal exuberant security deposit be paid or reservation canceled. in an obscure part of the advertisement it states a security deposit will be used if damage occurs
as stipulated in Low v Bouverie (1891), this term should be presented clear and unambiguously, it is not. the term itself need be clear and unambiguous to be a term as per Codelfa Constructions v State Rail authority of New South Wales (1982) 149 CLR , if it is unclear it is misrepresentation (vitiating element) Crown Melbourne v Cosmopolitan hotel.[2016 HCA 26]. Case law Cleary states that this term must be set aside from the contract
Additionally it is stated in the Electronic transaction act (ACT) 2001 that the contract is accepted and thus complete upon booking online (s13). No further terms can be added to a contract. the case of Oceanic Sun Line Special Shipping Company v Fay (1988) 165 CLR 197 demonstrates that the terms (amount of $ for deposit) which come after contract are formed are void.
Australian Contract case law aside. Airbnb own term and conditions preclude this hotel from charging a host security deposit after the in app transaction is complete. If they wish to include said deposit must be included in the checkout as stated here "If you’re a guest and you’re booking a listing with a host-required security deposit, you’ll be shown this amount before you make your reservation."
This is how I perceived the events and are of my own opinion. I hope in future the hotel can make changes to avoid such improper conduct. Instead of threatening last minute cancelation being able to accept they made a mistake.