Last Name

My daughter called me at work to say I received a call from "Josh" at the bank regarding my account. So, I called my
bank and the operator asked me what Josh's last name was and I explained that he hadn't left his last name.

When she asked for his department, I said that I didn't know. 

"There are 1500 employees in this building, ma'am," she told me rather sharply. So I asked her for her name.

"Danielle," she said. "And your last name?" I asked.  

"Sorry," she replied, "we're not allowed to give last names."