My Whirlpool is two years old. The freezer is on the bottom and every two weeks I have to chip off a sheet of ice. Wrote to Whirlpool and they said to turn down thermostat. It is on 3, but the ice still builds up. Can I fix this or do I need service.
Thank you.

When air is cooled the moisture in the air turns into water. Refrigerator have a place for that moisture to collect. That is often along the back wall of may be in the bottom.

From the collection place there is a tube, usually plastic, that that carries the water out and to underneath the refrigerator. There the heat from the coils causes it to evaporate.
It is not unusual for that drain tube to get stopped up.
Find that collection place and that drain tube.
Clear the drain tube.

If your freezer unit is a roll out drawer, remove that drawer and look for the collection place and drain tubing.

I'm not kidding you - I just returned from picking up the part that fixes that problem. It's a known issue.
Here's the video that describes the fix: https://www.youtube.com/watch?v=Tk24ISRzSRs
And here's the Whirlpool part number: W10619951
I'm doing this tonight.

Good video.

I'm defrosting the freezer now :-)