Does anyone else have a problem with the front seats?

What is your question?

It is almost impossible to get in and out of the front seat of the C300 without bumping against the side of it and this leads to breaking the interior plastic "clamshell" between the front and back of the seat on the side where it says airbag, which is an $870, non-warranty repair. It happened on mine after only 3,800 miles, I always got in and out with the seat all of the way back and I only weigh 218lbs. IMHO this is a design defect and cheap parts.

What makes this problem better or worse?

Nothing

How long has your 2017 Mercedes-Benz C300 had this problem?

A few weeks