If she doesn't want to go down the police route, if she feels awkward about it, then she can contact her local dog warden. The warden can issue an order for the owner to keep his dog leaded in public spaces. The police can issue a voluntary notice, or if escalated, can do the same of the warden. The difference with the police is if he is found to not have his dog on the lead, it gets moved up a notch to like a fine, or court hearing etc. (not sure of the specifics yet). Sorry to keep rambling on, dog on dog attacks should be taken seriously!