We have a Westinghouse WSE6100SA

Question

We have a Westinghouse WSE6100SA - side by side fridge freezer. Still under warranty. The repair guys have been twice now to temp fix the freezer, to no avail. the freezer is not freezing or I should say it stops freezing because the vent where the air flows through block with solid ice and when the defrosting cycle starts(warm air is pumped through the freezer) it doesnt stop and all the food defrosts. The purchaser, Repairer and Westinghouse/Electrolux are not fulfilling their warranty obligations... Please help