united cash loans still trying to get money out of old checking account miami, Oklahoma

My husband and i never took out a loan with these people.  i have had problems with them before and the bank took care of 1 problem.  they are now trying to take money out of an closed checking.  tried to sign in their website i have 3 email addresses and nothing.  yet they say we still owe them money.  they send e-mails and phone calls.  we never signed a document.  if we would have signed a document we would know it.  there is no telling now how much that they want.  can't these people be stopped?  they even put money in my old checking account.  we didn't ask them to.  2nd time my bank won't honor these nsf fees.  they said it was legal.  what is a person supposed to do.  someone has to stop them.  and i want my 300.00 worth of nsf fees.