Harassing Manager

The petite African American manager is crazy. She has harassed me twice now. Both times saying that I am stealing things and denying me to leave until security escorts me out. Both times security had spoken to me, and allowed me to leave myself, unescorted. I have never stolen anything out of the store and have given her no reason to accuse me of such things. Once one of the security personnels told me that she has done similar things before. I believe she may be racist for she does not say anything to anyone else!! I have tried to contact her supervisor but each time I never get an answer back.