Finance Debt Collector Company - Unauthorised Access to Info

I received an unsolicited call from the company. Their representative was rather ****y & also misleading. His claim was they are government authorised to contact people. The company was able to access my ITC/Credit details for which I never gave consent. When pressed for details of the company and how they obtained my details, and the consent to contact me, the call was ended. I traced the company operating out of Cape Town. Question remains, where did they get my data & who authorised access to my details & to contact me.