I renewed my car insurance on line last night. A woman from the insurance company has just phoned to confirm certain details.
Her: I need to ask you for your phone number
Me: You have just rung it. How do you think we are speaking right now?
Her: Do you have an email address?
Me: Yes, it is the one you mailed a confirmation to last night.
Her: Do you know your date of birth?
Me: Yes thankyou, I have had it for quite some time.
Her: Would you be interested in details of house insurance?
Me: I renewed my house insurance with you two weeks ago.
As you say, pleasant but thick. Look at it this way, it could have been one of those silent calls!
As for the date of birth question, if it was you making a call, then by being asked for your date of birth and maybe your address, then this establishes that the help desk employee is conversing with the correct person.