I sent a 3 page email once for one of the girls I advocated for, to get her into a high school she applied for. I told THEM basically “how dare they listen to loshan horah about this child when they themselves teach their students to stay far away from loshan horah.” I said L”H is a killer and destroys families and nations. They should never listen to loshan horah about anyone and they should make up their own minds about the applicant and not take what they heard at face value. Only listen to the good they heard about the child, and listen to those teachers and mechanchim that had good to say about her because they certainly told the emes. Speak to the child yourself and make up your own minds and then give the child a chance to prove herself.
The head of the school showed up on her doorstep the next morning and told her that whatever happened in the past stays in the past and it is not his concern what others said about her. He was happy to welcome her to the school and it was a fresh start and clean slate for her. She had her best school years in that school. All the teachers loved her and she went on to seminary in E”Y. She in now very happily married.
If there is anything you can add to your application or anything that someone else can add to your application about someone being motzi shem rah on you, and that person ruining your life and good name, that might help especially if you don’t name that person, just say that it was an unfortunate incident or misunderstanding and that every story has two sides to it, but you are following Torah guidelines and are not bad mouthing that person, spreading l”h or being motzi shem rah on that person.