Upvote:7
If, as your comment implies, the hotel only mentioned a cancellation fee in a subsequent e-mail then you owe nothing. The hotel cannot force you to pay a fee that was not agreed at the time the contract was made (i.e. during the telephone conversation). However, if you were made aware of the cancellation fee during the phone call then you are probably liable to pay.
The hotel could bring a claim against you through the European Small Claims Procedure. Details of the procedure can be found here: https://europa.eu/youreurope/business/sell-abroad/resolving-disputes/small-claims/index_en.htm