Had a similar problem on my fridge, but no frost. The freezer worked but the fridge didn't work on gas. The service guy pointed out that my model had a sliding thermostat lever on the back (unknown to me) and apparently had gotten slid down to the lowest setting. Also, there was a plastic "drain pipe" for lack of a better work that was suppose to have some kinda plastic valve on the end.
I guess it wasn't put on when installed (QC at it's finest) and he said that it had something to do with airflow backing up into the fridge. Honestly, I have no idea what he was talking about, but he said it fixed the problem.