How can I fix my Samsung RS21DCNS?

I have a Samsung RS21DCNS. We do not have the water and ice dispenser connected so there do not work.

The freezer is working fine (-20 showing on display) and the fridge was working fine until Thursday (4 showing on disply)

We had a power cut on Thursday and the power was off for about 15 minutes. When the power returned the display went up to 12 and has been playing up since. Sometimes it goes back down to 4 but within half an hour its gone back up to between 10-12.

Please can you advise on what we can do to sort the problem