Refridgerator not cooling n freezer iceing up.

This fridge is less than 2 years old really disappointed with frigidaire quality. Had a appliance repair guy diagnose the problem and paid $45 for the service call but decline for him to do the repair for $320. Remove the cover 4 screws holding it on top of fridge the defrost timer is inside 2 screws and you just unplug and replace with a new one. The defrost thermostat is in the freezer compartment, remove the ice maker if equiped then remove back cover, cut out the old thermostat n crimp in the new one. So far the fridge is working but still not getting as cold as before but good enough to keep things safe. Thanks to partselect.com i saved a bunch of money doing it myself.