My Electrolux ERF 2830 type B257726 fridge freezer is acting up. The freezer is working fine but the fridge compartment is currently warm, over the last few weeks if I turned the thermostat up to 5 it was literally freezing drinks etc. and now it's the opposite.

This is a fairly common problem with most Frost free Fridge freezers. The system relies on regular automatic defrosting, and if there is a fault in that, the cooling cycle is seriously affected.
The problem could be as simple as a blocked defrost water drain tube, or more complicated such as a failed de-frost heater, defrost timer, or drain tray heater.
To check and repair any of them, is quite an involved process which involves stripping a lot of trim, and other parts just to get to them.
I would suggest that you get a qualified Refrigeration Engineer to repair it.
I hope this helps?

Often times their is a fan from the freezer section to the refrigerator section, of some brands of boxes. If the fan goes out, the refrigerator sections no longer cools.

Sounds like a gasket issue somehow warm air is getting into your unit maybe through the ice dispenser

Most likely you have a defrost problem. On some electrolux models the cooling tube (from the freezer compartment to the fresh food compartment) get blocked by frost. If you do not feel air flow (when the fan is operating) then that is the most likely cause. Which means that something in the defrost circuit (heating element, thermostat or defrost timer) is not working correctly.
But before you check them make sure the fan is operational in the freezer and that the condenser grill under the unit is clean.

It sounds like one or more of your cooling tubes is blocked. Either you have a ice or frost buildup on your freezer side or something else is blocking it.

I would suggest you take a look behind the panel in your freezer and use a hair dryer or heat gun to blow warm air down the cooling tubes.

check appliance blog .com and type in your make/model,sometimes there are fixes on there

check for defrost element not working ice build up will cause it not to cool fridge,check continuity of element with unit unplugged!!!if continuity ok then check defrost timer!!! :)

Possibilities include inside fan unit not running for some reason, thermostat cycling the unit off before its cold, compartment light staying on, damper adjustment set too warm or broken or blocked. There are others but less likely.

Check the back wall of the freezer compartment for ice buildup. Sounds like you have a defrost issue.

I had the same problem; the top fridge compartment was warming up to 14C while the freezer compartment was starting to defrost (frozen stuff was starting to become soft. I took the rear wall off the freezer compartment and found it all iced up. I defrosted it with a blower heater then powered it back up. It all worked fine for a month when the same thing happened. I figured that the defrost cycle wasn't working. I located the defrost timer on the rear right-side of the fridge. I rotated it several times and found that the fridge was turning on and off. I rotated it until the fridge turned off. I waited 5 minutes then stuck my head into the freezer compartment and felt the rear wall at the bottom where he drain is; it felt warm so I guessed the defrost heater element was ok. I ordered a defrost timer and installed it. I haven't had a problem since.