How can I fix my baumatic wine chiller ?

The wine chiller switches on (the light comes on), but it is not chilling the wine - remains at room temperature. It is a Baumatic, 15 bottle chiller. We have only used it a few times (do not keep it switched on unless we have a need). So far have been unable to use for a while because it is not working. Obviously electric supply is there, but no refrigeration.