Claim to be National Credit Management when u ring back with your First name & Ref # left on your voicemail.
I called back & gave them the Ref #. The guy wanted my full name, phone number, Dob and address etc - to which I refused because this sounds like a scam to get your identity details or worse.
A legitimate reference # would bring up my details so they could tell me what it's about.

Claim to be National Credit Management when u ring back with your First name & Ref # left on your voicemail.