How many security questions are needed to be asked before a complaint will be dealt with?

Hello everyone,

I am just wondering if it's normal for almost every Virgin Media team member to be asking questions like your full name, account number or post code and house number, name of the account holder, email address, amount of latest bill, last 4 digits of bank account, your date of birth - and to also to be sent a form of your ID? 

If so, why do they ask people to set up a memorable word when first setting up your account? What is the point of even doing that if you are never asked to verify any of the characters? Genuine question. I just want to make sure I'm not the only one having to endure this incredibly tiresome process.