Fridge not getting cold

[sheddy]

We have a Baumatic BL18A built under larder fridge that isn't getting cold enough. It has been working fine until just before Christmas and then we noticed that the butter wasn't as hard and the milk was going off ect. Before I throw it away(it is only 3 years old) is there anything that I can do to fix it.
Everything seems ok at the back ie the compressor and pipes don't look to be leaking and are nice and clean.
It seems a shame to throw it away being as it is only 3 years old and if I can fix it we could use it by putting it in another room that isn't being used.
I would appreciate any advice on this

 

[Burnerman]

Can you hear a click from the thermostat as you turn it up - and can you hear the compressor actually running?
John

 

[sheddy]

Hi Burnerman,
When I switch the fridge dial round from 0 (off) to 1 the compressor switches on straight away. I cannot here anything else even when I turn it up to the max (7) I have left it running on 7 and put a thermometer inside to see if the temp goes down.( It didn't do before it wouldn't go lower than 16 degrees).