The bus to Chora Sfakion goes through Frangokastello or at least very near it . There certainly used to be one bus in the morning and one back late afternoon - probably also the reverse .I suggest you go on a day trip first , get the lie of the land, decide whether you want to go back and book accomomodation if so .But if you are going in high season it might be difficult to get accomodation at short notice
roger
