"Good afternoon, this is Affinity Water. Am I speaking to Mr. S.?"
"Yes, that's me".
"To confirm your identity, please state the first line of your address".
"You tell me what you think it is, and I'll confirm if it's correct. You called me."
"That would break GDPR laws if I did that."
"Well, I see no point in continuing this conversation. I know who I am, I don't know who you are."