Samsung side by side fridge freezer – fridge not working

Hi, i’ve got a samsung RS21 FCNS side by side fridge freezer, now unfortunately out of warranty (isn’t that always the way?). The fridge display started flashing a couple of days ago, indicating that the temp was rising, which it indeed was. Now there is no cooling at all in the fridge compartment, the display is reading 22 degrees and my beer is getting too warm to drink (almost 😉 ). The freezer side appears to hold it’s temperature steady at -18 with no problems.

I have tried turning off and back on, this has no effect whatsoever. The only difference i have noticed today is that occaisionally the fridge temp readout is lower, about 13 – 14 degrees, but the next time i look it’s back up to 20 plus. I don’t have a thermometer to determine whether or not this lower reading is actually representative of the temp in the fridge.

Are there any other tests i can do to diagnose the problem myself? Ideally i could do without the expense of getting an engineer in as in the last two months the boiler, dishwasher, and fridge have all packed in, although looking back through other related posts it looks unlikely to be a DIY job, but you never know 😕