I also experienced your concern, i know some access number that really deducted to your load even your not registered to it..
or much better if you call the hotline and request all the 4 digit access number to deactivate or block all the access number to your account, but i believe you need to wait for that after 3 working days, so for the meantime, if you receive an access number try to send CHECK to the access number you received. you will receive a prompt message informing you if you have registration, and if you have, you will see the a instruction on the latter part of the message on how to deactivate the subscription. Don"t worry, that is FREE of charge, you just need to have maintaining balance of at least 2.50.
hope this help....