Hotpoint Mistral Recurring Problem

Hello again…
Reference a previous post: http://www.ukwhitegoods.co.uk/modules.p … nt+mistral
the thing worked for a while and now the problems have started again 🙁
Temperatures of both fridge and freezer fluctuating and the odd ‘whirring’ sound. It has been cleaned and defrosted.
Any ideas or reasons for the behaviour would be greatly appreciated! If it is the condenser fan, are the parts available here?

Thanks
Jon