Phoning Constantly looking for someone else

I constantly get calls from the supplier mentioned above. They request to speak to Ponsho Blandina Makhafola. I have now numerous times asked them not to phone me as I don't know this person and they obviously have the incorrect number. I have also requested that they take my number off their database. Still they continue to phone me. I am now fed-up! Seriously? Can't they follow a simple instruction. This has been going on for years now.