Had a problem earlier in the week that I made a complaint about. I've just had a phone call from an 0800 number (since checked and it is a genuine ID Mobile number 0800 049 1300). 

Thought it was a scam but may have been to do with my complaint so started to go through the SECURITY questions where I was asked my account pin number, really?

So I gave an incorrect one, wrong address and DOB but it appears I passed the security checks!

So I told the caller they weren't real and "F### you" before I hung up.

My question is are these security checks worth anything? Was this a genuine call l? How do I tell? 

Male 57yrs, mothers maiden name Reynolds, first pet Tiddles, Ford Fiesta MkII