"At that point it is up to you as to whether you choose to accept that new rental contract (which could in theory have a different price and a whole different set of terms and conditions) or whether you choose not to accept that new rental contract"

This is where it is a bit grey at the moment. The new owner/mc are making things up as they go along and no new offer of contract has been made. What's to say they don't next week decide the payment doesn't inlcude electricity because that's the way they work, or on arrival a whole host of other changes have been made. In accepting the contracts in place for bookings the onus was on the new people to ensure they could work with the existing bookings or decline them. They may have to take a loss on some of them compared to what they would like but they were booked in good faith and the Guests deserve to have their expectectations (and contracts honoured).
I'm sure it was not sold as an ongoing business , rather that the existing bookings were a bit of a bonus and in what could be a good chance to earn loyal repeat Customers, they are letting themselves down big time by alienating those who have already trusted them with their hard earned money.