Appropriate way to advocate for one's self - I'll be ignored due to low GPA

I’ve heard about contacting the schools you’re applying and letting them know you’re interested and that you’ve applied but your application has probably been filtered out due to the range of acceptable GPAs. I don’t know how to go about doing this or what to say without being obnoxious. Who should I specifically try to contact? Should it be in e-mail or over the phone? There are so many applications that fit the guidelines, how can I convince them to spend extra time to take mine out of the trash?