Their General Counsel is:
John Finneran, Rr.
SVP, General Counsel & Corporate Secretary
Capital One Financial Corp
1680 Capital One Drive
Mclean, VA 22102-3491
(But he probably has nothing to do with whatever you want to resolve - that's almost certainly handled by somebody within the legal department.) The number for the headquarters is 703-720-1000. Ask for the legal department. You can also
try 703-205-1105, which is listed on some old correspondence as a number for their legal department, but you may end up being misdirected.