Salut credit card / credit card company closed my account without notice

I had this credit card since 2007, never made a late payment, recieved a credit limit, and just recently went online to salute to make a payment. I always pay over the amount due. I noticed on my account summary the credit limit stated 0$. I emailed them to find out what was going on and after several days just recieved a email stating that the account was closed a i should recieve a letter stating why. I am just confused, how can they do this and do we get a refund for all the bogus charges i have paid. A monthly maintenance fee and a fee to pay online. And what about the remaining balance, how can it just go to 0$. Do i have to keep paying on this credit card i no longer have. I am tryint to get my credit together and now this. What can de done????