The club code of ethics, Item 8:

8. To fulfill all contracts and agreements which I may make, either oral or written; to make prompt payment upon delivery; and to return immediately any item that is not satisfactory.

Ask whomever is in charge of club memberships if the person is in the club. If the person is not in the club, run a post with the name and ask if any club member can help out. Some of the time these are honest mistakes or things have come up that delay responses. Some times, people try to flat out cheat you. Let's hope this is just a communication snafu.