Mistral frost free freezer won't freeze properly?

Hotpoint Mistral FrostFree Fridge/Freezer - Fridge works fine but freezer temperature won't go below -6, warning light doesn't light (what temp should it come on?). Fan at back of top freezer box runs but not all the time. Have just started getting pools of water/ice at back of bottom drawer stopping the drawer opening. Is there a possible blockage/Ice build up giving poor air flow or is it electrical?

As access to the back is severely restricted, before I attempt to move it any feedback or ideas are appreciated . Thank You