Assuming your account is a consumer account (as opposed to a business account), the Fair Credit Billing Act, which is part of the Truth in Lending Act, does require them to send you periodic statements at the end of each billing cycle, if there is a balance of over $1. You might want to see a consumer lawyer about this situation. Most will provide a free consultation, and take good TILA cases on a contingency basis. If you don't see an attorney, I suggest filing a complaint with the Consumer Financial Protection Bureau.
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You could always have gone online to view your statements. If you had made purchases you should have known you had a balance. Clearly you are not having success with this company. Cancel you credit card. Pay off the balance. Consider shopping elsewhere for your unmentionables or use a VISA, MC or some other credit card rather than a store card.