My freezer stopped working, please help?

we have 3 fridges with top freezers and one chest freezer, bizzarely all four freezers have broken down within a matter of weeks of each other. The fridges continue to work without issue but the top part will no longer freeze, they have all been cleaned out, no build up of ice, in two of them if you put something frozen in them it will keep it frozen if it is completly solid but will let say ice cream soften and it will not freeze anything not frozen you put in it. The third fridge freezer was making a hum and clicking sound, the others gave no warning. The chest freezer just started to defrost and the alarm light came on there was nothing wrong with the seal or too much ice on the sides, we empied it, cleaned it out and restarted it, you can hear the motor running but it is not freezing at all and the alarm light is still on