Breach of privacy of information

On the afternoon of 12 December 2018, I received an unsolicited call regarding fibre installation. When I asked the agent, Solly, to please confirm where my details were obtained from, he tried to give me any other reason why I am being called, except where my contact details were obtained from. If my details were not obtained from myself, then where did Vumatel get my details from in order to make this call?