If you believe you're being bullied, harrassed or victimised by a student, there is a process outlined in the University's policy on dignity and mutual respect ("the policy"), which is summarised below. Wherever you find yourself in the process, you should seek support from your HR Manager.
Do you feel comfortable trying to resolve the issue informally? Section 7a of the policy will give you some ideas on how to go about this.
If you don't feel you can resolve the issue informally, or you've already tried and this didn't work, you should discuss the matter with your Line Manager or Head of School/Service to help you liaise with the student. Section 8 of the policy goes into a more detail.
If discussion with your Line Manager or Head of School/Service has not helped to resolve the issue, you should submit a formal complaint in writing through the University's disciplinary regulations.
If you need help, support, advice or clarification throughout any of the process, please don't hesitate to contact your Faculty/Service HR department.