How Can I Convince My Parents To Let Me Get My Nose Pierced?

I'm Thirteen years old,Female . I have been wanting to get my nose pierced for Two years now. when ever i ask they will say no ill be like WHYY and they be like NO ... we know some one who agreed to pierce it for FREE! so HOW DO I CONVINCE THEM! i wore fake pierceing befor because my mom sai dbefor i got it pierced i would have to wear fake ones for a week wich i did i remided them what they said and they just said they never said it so WHAT DO I DO! i have done evry thing i can think of PLEASE HELP!!