GE Profile Top Freezer too cold, refrigerator too warm

Repair man dx’d a dead fan in the freezer compartment. Post replacement the fan ran quietly but temps did not properly adjust….freezer went deep freeze w/ double digit below zero, while refrigerator stubbornly remained in low 50’s. After 3 days the freezer fan began to “clatter”, which makes me suspect a sub-standard quality replacement. I have also heard about icing in the channel that carries the cold air from the freezer fan to the refrigerator, but my repair shop is professing ignorance. They came out again and merely adjusted the temp controls, which were already on 0 and 37. Any ideas?