Your issue sounds like a mess. Should've been fixed by the first CSR. What you probably need to do is either call/email and insist on merging and/or deleting any duplicate accounts. This way it'll prevent future issues that may arise. It shouldn't be too hard if you signed up for all the accounts using the same info.

Do you have a physical card for any of your accounts? Do any of them have any history of play? I would try to look for and keep the one with any history of play. Try to sign on or register with an account where you have the number or I guess try whichever ones you have.