[Oh for the love of- At least the other Servants who claim to know him don't use his name, if they even know it! Then this guy comes around and acts even friendly. What was going on?]

Wherever you've learned that name, don't yell it so loudly. I don't go by it and I'm not the person you claim to know.

[If he hadn't met other 'Chaldea' Servants, this would be a much less "polite" answer.]