Bad attitude of call centre agents

Today i received a call from one of your call centre agents regarding an account of mine, the call did come in from an unknown number , are your company afraid to show your identity, why using an unknown number, when the agent stated talking he insisted that i give him my date of birth, this is one thing that i do not do over the phone as i have no certanty that the call is from your company and with an unknown number to it can be anybody phoning making use of any company name. There is to much ***** that happens that way. They also started phoning on my wife cell phone number, where did they get that, i would appreceiate if a senior member of your company can contact me to discuss this matter of the rudeness of the call centre agents as well as their pushing for private and confidential information that they do not need to know.