**** absa calls and SMS notification

I called the ABSA call center to get some idea how to prevent absa employees to call me on the cell and ask for client detailed verification before the conversation could be continued. I think this could be a **** call would hold absa liable for non disclosure of such information. I just find it strange that I must disclose my details on the phone. How many of me are there that could answer my phone incorrectly compared to people calling me without verifying who they are. It could be hundreds of people at ABSA with my detail that could be ******** me. Any comments other than paranoia would be helpful.