credit card statement question

I went bankrupt a year and a half ago. I have a business (incorp) which had an Amex card with a balance, never missed a payment and still owed money after the bankruptcy, a month after going bankrupt they sent a letter that I had to send in the card and pay the balance in full. They stopped issuing credit on the card. I never paid them in full but kept iup the payments. I have not had a statement or call or heard from them in all this time...should I keep paying, I dont even know what the balance is and am afraid to call them. It would be nice to know the balance but do not know what the law is in a situation like this...please advise.