Inappropriate experience

In 2017 I booked a 3sleeper me and my friends 3 adults and 2kids under 12 (5) people paid accordingly with no misunderstanding, in 2018 I booked with my kids 1 adult and my 4 kids under 12again paid accordingly with no misunderstandings again 2018 it's me and my kids again but now with no any thorough clarification nor explanation now I'm expected to pay extra for my kids whereas 3years now consecutively been booking at Valley View holiday flats in Dbn without paying extra for anyone. Here is the set up of the room 1double bed 1single bed and a sleeper couch, I stand to be corrected and will fully take the blame if I'm wrong but 3years I'm a row booking a same room with 4&half people in it but now I must pay extra.