There are many agents at present, but I want to ask you a few questions. Dare you give all your personal information to a stranger? Can you guarantee that he won't use your information for other purposes? Get your information and do it. Two for you, you know? Taking your card to cash out will give you big problems, and then the bank will give you trouble. Would you like to touch these things?
I suggest you handle it through formal channels.
It is not illegal for you to choose an agency, but you have to bear all the above risks.