STOP CALLING ME AT WORK FOR PRESCRIBED DEBT!!!

SSDA keeps calling me at work even after I asked them numerous times that im not allowed personal calls. Plus they are calling and sending emails for prescribed debt. I have asked them numerous times to send me proof that it has not prescribed, however they just harass me at work every week. Im sick of it. If they call me at work once more, I will lodge a harassment complaint with the credit ombudsman for prescribed debt.