Even with the dial turned down to 1 we are getting fizzy drinks can exploding inside the fridge, bottles of tonic doing the same – doesn’t seem to matter if they are in the fridge or in the door

It’s a built in fridge. There is a built in freezer too but that isn’t next to the fridge

Anything obvious I can check before I call someone out?

when our under warranty motorhome fridge went temperature wonky the tech support guy said step 1 was a thermocouple and sent us a new one – luckily on the motorhome fridge is was a bolt on/plugin job but it fixed it, can you find a diagram on tinternet and see if it could be the same

my other idea is to check if it feels like the dial is actually doing something/connected ok

Anything obvious I can check before I call someone out?

Yes, try turning up the dial to make it warmer, not down.

Even with the dial turned down to 1

Is it in a cold place? Fridges in garages or cold houses can be too cold as they cannot cope with ambient temps too low.

The thermocouple (can look like a couple of wires twisted together and wrapped in insulation – because that’s what it is) needs to be in a cold  place in the fridge. It’s like the thermostat. If it’s been dislodged, and it’s always warm the fridge will just keep cooling and cooling.

Put the fridge in the oven?

As above try the opposite end of the numbers before anything else…

It’s probably degrees rather than 1-5 in coldness

You know who to call…