I bought a lot of frozen party food this morning and brought it home, then filled the deep freeze in our fridge freezer that is set at - 18 degrees. I saw that there’s a ‘fast freeze’ button so I pressed that to give the freezer temperature a bit of a boost to ensure the frozen food I had bought would chill down quickly. But when I checked the temperature 2 hours later, it read -30 degrees! I then belatedly read the instructions for this button and apparently it’s used for freezing fresh food. I immediately switched it off. The freezer temperature is slowly increasing. Can you tell me if the frozen food is still safe to eat as it will have been deep frozen then just frozen at - 18 degrees..?