Idiot, problem-causing tele-consultant

We got an sms that the cell phone number on our banking profile had just been changed. It was not us, i.e. someone hacked our account. We immediately phone the number it says to report it. We tell the tele-consultant that someone has just **********ly changed the telephone number on our profile. He asks the security questions all of which we answer correctly. He blocks our account because we gave him "the wrong telephone number for the profile". What did the person not understand about the fact that we just told him someone changed the number and it wasn't us?