Hotpoint Mistral ff72 - fridge temparture is showing 18 degrees?

I have a problem with the fridge tempature on my Hotpoint Mistral FF72 Frost Free Fridge Freezer.
The tempature is showing 18 degrees, however the manual says it should be between 2 and 6 degrees. I have tried to reset the tempature but it does not work and the fridge compartment is not very cold as it used to be. I think it is only cold as the freezer compartment is working fine and that is showing a constant -22 degrees.

I have ensured the grille at the front is free from any dust but other than that I am at a loss. The door closes fine and there are no cuts in any of the seals. There does not appear to be any air coming from inside the fridge (the air vents near the light and that) so it might be a fan issue or something but I need guidance on how to change that if possible.

Any ideas before I go buying a new one as I am not enjoying my warm beer and with the World Cup coming up this is not good?

Many thanks for any help.