Fridge thermostat or worse?

Hi all


Recently had to perform a 24hr defrost of a Russell Hobbs frost-free fridge freezer model RH55FF173R.


After a successful defrost, the fridge freezer booted up again with no problems in the morning, but after spending the day and most of the evening out we returned to a fridge compartment that was almost room temperature. The freezer too had warmed up with the fan not moving.
I had cleaned the fan and a few other dusty pipes so knew it wasn't the motor or fan itself.
Automatically thought it needed resetting, so quarter-turned the small plastic reset dial at the bottom rear left of the machine and it fired up again, no problem.


Following morning, warmer fridge and fan stopped again.


One major difference I noticed was that the numbered temperature control dial (in the same small unit as the light) at the top of the fridge compartment did not 'click' whilst moving from 0-7 and back, and hasn't over the past 3 days.


Any ideas what the problem could be? Could something have happened during the defrost?


Cheers in advance