I have the same problem, Hotpoint service engineer came out (£89.98 gone) and said that we needed to turn the appliance off for about 3 days. Then re-start (really worth the £89.98 callout charge). All is now OK but the ice is now building up again on the bottom shelf and periodically de-frosts and leaks over the floor. It appears that if the fridge door is left slightly ajar for any time that there is a build up of ice in the rear air vent (through which the cold freezer air is drawn in order to cool the fridge) until such a time that it blocks thus meaning the fridge ceases to get cold air drawn up by the fan hence it warms up. I tried to turn it on after a 24 hr defrost but it did not work, next time I think I will use a hairdryer or such to speed things up. It took the 3 days to defrost sufficiently, I guess it means that at least the unit is well insulated as it took 3 days to melt the ice plug. However I wish I could earn (£89.98) for dispensing advice such as "turn it off for 3 days", what a design flaw !!! I assume there is an underlying design flaw and or sensor or fan failure but the engineer assures me things are OK
Bruce Agnew, Disgruntled Hotpoint owner & professional engineer in the aeerospace industry, November 2007