AFTER MUCH RESEARCH I KNEW THIS WAS GOING TO BE GREAT  .. It didn't fit properly. i have a 1 piece Kohler 1993 model. this seat would just not adjust to sit well because of the curvature of sides. Very Very upset as it was advertised to fit MOST round toilet bases.  it does not..

Now even more disappointed that it appears it can't be returned...IS THIS TRUE. 
PLEASE ADVISE