BEKO BC50F problem - Only fan is running, freezer seems to shut down and so is fridge

Hi Refrigeration-engineer.com friends.
we bought a Beko 9.1 cu.ft model BC50F in April 2009. Its a fully integrated fridge freezer which never gave us a problem so far.
From past few days though we noticed the freezer is not working and all the frozen things have actually melted. e.g. icecream and peas have become all moist.
the freezer fan seems to be working sometimes - it switches on and the fridge is still cold too. but we can see water droplets inside the fridge which we never saw or noticed before.
The freezer used to make noticeable noise when it was working properly, now it seems the noise has gone down considerably and though the fan rotates we can't seem to get things cold enough.
---
I called Beko who said out of warranty and suggested to call recommended provider Domestic General. Calling them it seems there are two policies - one if things are already broken down and needs to be repaired an extended cover or direct extended cover if things are ok. Obviously paying 60-90£ to call someone to look at it and then another 50-100£ may mean I am actually paying the price of the fridge freezer itself.
What do you recommend (A) can I solve the problem myself, if so what should I do - i checked this forum as well as the manual and don't know if anyone had same problem before (B) Any recommendation on how to get it repaired at reasonable price now.
Thanks Ritu