Samsung problem – fridge not cold / freezer freezing

Make/model: Samsung RL38SCTB
Model code: RL38SCTB1/XEU
Serial number: C73441AS900451 J

Hi
This is my first post on here and I’m hoping that someone can help. I have an older Samsung Fridge Freezer and over the last week or so, I have noticed that the fridge isn’t particularly cold. At the same time, the freezer is icing up and everything in the freezer (drawer fronts and all contents) are covered in thick frost.
I have taken the freezer drawers out and the air coming through the vents at the back of the freezer seems very moist. There’s a visible mist coming in. I have tried altering the temperature of the appliance but this doesn’t seem to make a difference to the fridge compartment.

I’ve had a look at the back of the appliance but there are no obvious issues apart from an area of plastic at the bottom which looks as though it has suffered from heat damage (it’s warped a little but the closest thing to it is a length of piping within the back of the appliance).

I should add that this fridge is in my garage (attached to the house) and has been happily working for over a year since we moved into this property.

Any advice would be gratefully received. I’d hate to buy a new one if there’s potentially a way to get this one working properly again.

Thanks,
Rob.