Cold callers

I was cold called by Hollard Life - I explained that I had opted out of calls (National opt out, DMASA) and asked to speak to the manager to enquire where the company acquired my data from. I was spoken to by “Lawrence”, who refused to give me his full name and then hung up on me when I said that it is not fair that he has all my details but refuses to identify himself. If you’re not doing anything wrong, your identity shouldn’t be a secret, especially if you’re calling people on their private numbers.