Hotpoint FF72 Faulty Fridge Temperature

Hi,

I have a Hotpoint Mistral FF72, with a fridge problem like most people I have read about on your site.
Freezer is working fine at -22. The fridge is at room temp. I have done the first action by doing a defrost overnight which solved the problem for 2 days.
Now I am back with the fridge at room temp. If I turn the power off and back on I get a code P1. I assume this is a Thermister Failure. Is that correct? If so, which part numbers do I need to order new thermisters?. I know my way around most things with this looking straight forward; I hope, therefore I am looking at fitting them myself. (power off of coarse) Do you have a guide for changing them, as they look well fixed in within the freezer part.

Cheers
Mark