What can I do when my credit card processor withdrew all my money from bank account without any reason?

I used a nationwide credit card processor but they cancel my account after one customer made an inquiry. The inquiry is the customer forgot our name and only asked for a copy of receipt. The processor suspend our account even before sending us notice about the inquiry and then made up own story after we replied them in time. We do not have any chargeback or fraudulent transaction in record anytime. Latter they went into our bank acct and withdrew all the money until reach the overdraft limit. They refused to return the money until four monts later after they applied unknown charges.