Problems with Standard bank

I never had an account with this bank, but for the last 9 years, since I have my home telephone I keep on receiving calls. . In this time I have about one phone call per month asking for a certain Me Bester. When they started with the calls, I explained that I don't know who this is. I have this telephone number since 2013. I asked them to remove my number from their database, and guess what, they did not. If the calls are not from a machine, it is someone to whom you can speak. I even went to the local Standard bank, and they could not understand and help me. I asked them to contact their head office, but it seems even they could not do it. I asked to speak to Management but they told me they can't transfer the call, so I asked them to ask the manager or a supervisor or someone who knows what to do, to phone me. This week I received a call on Monday morning, and I explained that I have no idea who this person is and that I have this number for nearly 10 years and in all that time they could not get their data in place. I asked her to never call me again, and guess what, this morning I received another call and the very same story again. So I asked her to either let someone from management call me, or I will take further steps. Needless to say, no-one responded. This is badgering and trespassing of my privacy and this is utterly unprofessional. I hope you can assist me in this.