Broken John Lewis Fridge Freezer

I bought a John Lewis fridge freezer (model number: JLFFW2001) mainly for the 3 year guarentee that comes with it. Would you believe it – the fridge freezer broke down just a few months after the guarentee had run out. Things were defrosting in the freezer and the fridge was too warm. Got a repair man around who reckoned it was the de-frost probes so he went off to order some new ones. When the new ones came he was a bit flummoxed as the colour coding on the two wires was now the different way round to the colour coding on the original ones. He installed them as he thought best but after a few days the same problem occured with the fridge freezer being too warm. He then swapped the probes around the other way but a few days later the fridge freezer is still not working. On his last visit he mentioned that it may be the control board that doesn’t work and that we might be talking mega-bucks.

So, do I stick with this repair man and have him round again (i.e. was he right to fit the probes or did he get the problem wrong in the first place)?

And if it is the control board, is it economically viable to get it fixed or should I buy a new fridge freezer (which I am kind of loath to do as it cost me £500)?

Any advice gratefully received – am trying to keep all my food cool in the utility room but the warmer weather really isn’t helping……..