Sounds like it could be the thermostat that has gone on your old fridge/freezer.

If it is less than 5 years old could be worth getting an engineer in as a replacement thermostat would cost less than £50.00 fitted.

Otherwise we use Hotpoint and have had no problems so far (touchwood) although Samsung and LG are getting very good reviews and if we ever had to change ours we would go for a Samsung now.

Look at ordering through either TopCashback or Quidco so you can get some money back - every little helps!