African Violets need help?

African violets will tolerate 60-80F but prefer a temperature of 70F. They will suffer in the cold and in most severe cases as in yours the leaves and flowers will wilt and the plant goes into shock. Often it is not possible to save them unless you act immediately. You have nothing to lose by trying.

First move them into a warm draft free place. Don't hack the plant off to nothing as has been suggested but do remove any parts that are dark and mushy to prevent the rot spreading to the rest of the plant. Stop watering and fertilising but give the violet high humidity. You can do this by popping it in a clear plastic bag and sealing the top. If you have been successful in your rescue attempt there should be signs of recovery within a few days. If it is recovering leave it in the bag for another week. Then take it out and water and fertilise as usual.

It is also best to water African Violets with tepid water so that their roots don't get cold.

Prune them drastically and don't heat them. It will only dry them out. Pruning cuts out the need for more water than the roots can supply. If the roots are dead, you will have to buy a new plant.