My whirlpool refrigerator will not get cold in the bottom half of the refrigerator and the freezer will not freeze. It is a frost free refrigerator but has began forming a hug layer of frost and ice on the freezer wall closes to the freezer unit. The refrigerator is only five years old but is no longer under warranty (ironic). The model GT2SHMXMS01. Could you tell me what the problem could be.