Hotpoint Future FFP187B

Hello
The Fridge Freezer is approx 5 years old; we brought it second hand 3years ago. Until recently it has run very well the only problem being a build up of ice around the bottom draw. Which was cured by the use of a hair dryer once every 3 months.
3 weeks ago I failed to get the hair dryer out and the build up of ice became so great it distorted the back panel so much that you could not close the door. At this point I am not sure if the appliance stopped working or the door being open made the food inside thaw. But we lost the lot.
I unplugged it and left it to defrost for 2 days. Then unscrewed the plastic air duct panel on the back of the freezer compartment and there was still a build up of ice on the freezer element. I removed this with a hairdryer. Then turned it back on. The compressor runs and the fan runs and if I touch the freezer element it is cold enough for my finger to stick to it. So I reassembled it. And left it running over night. In the morning the compressor is still running and if I open the freezer door the fan is running. But the fridge or the freezer fails to feel cold and it has that mouldy smell to it.
I really don’t like to dump things. Id rather spend 50 pounds on this than a hundred pounds on a second hand replacement. ANY IDEA’S OF THE FAULT PLEASE.. Thanks