hi there, I have just had a kitchen fitted & because my fridge/freezer needed replacing I opted for an appliance housing unit & would then buy an integrated f/f – I have taken the internal measurments of the housing unit & the depth is 500mm-however all f/f seem to be deeper than this-should the back panel have been left off & also do I need a vent fitted in the “kick board” (I,m sure I saw a “vent” when the units were being unpacked) but it,s not fitted anywhere,also should there be a “top” on this unit? at the moment it is a fully enclosed cabinet/cupboard – advice desperately needed please,