Even if the company doesn't have information online, write the store manager a letter. You are probably not the only teenagers she has treated poorly, and they can use the letter to either try to correct her attitude or take steps toward her dismissal or disciplinary action. They do not want an employee that drives away customers! Maybe they'll have her work in the stockroom, or somewhere away from people.

If you know her name, include that, otherwise just the date and time you were at the store, and give your receipt number so they can verify things.