Thank you for the polite note; I am always appreciative of any disciple of formality, there are not enough of us remaining. I would be delighted to offer my assistance in any capacity.
I'm most available in the evenings, if I may invite you to my home for tea. I imagine that would be the most comfortable for us to discuss the circumstances of your difficulty, so that I might determine how best to help you.
My flat is at 435 East 52nd Street, 23rd floor. I'll leave your name with the front desk. Let me know if you'd prefer this evening, or tomorrow. Around 8pm, perhaps?