Nu Debt stop the harassment

This company keeps emailing me stating that I have SABC debt. I left SA 11 years ago and informed SABC repeatedly over a period of 3 consecutive years. I sent all the requested documentation to SABC. Now, 11 years later, Nu Debt emails me every week with urgent payment notices. I have also told them that I left SA in 2014 but this had not stopped the continuous emails.