Brittany Ferries

Booked our ferry crossing, but i waslooking through some site reviews and came accross one that pointed out the Deck Number on the Ferry. They pointed out that  there Cabin was below the Car Deck ? and felt uneasy sleeping knowing that they was sleeping so low down in the Ferry.When we booked with cc the deck no was not discussed . I rang cc before and they rang Brittany Ferries she came back and told mewe was  on Deck 9 . Anyone had any worries regarding this. I have had  a bad experience on a  ferry years ago just hope this is going to be ok for me i may be worring for nothing !!!!.