You will need more information about this situation. How could the company take any money without knowing the account number & without specific authorization from you?
Get the answers to these questions first, then ask your question again.
Hope this perspective helps!
All of us lawyers who are answering this are assuming the company doesn't have a judgment against you. If there's a judgment, then they can garnish your bank account and take money out.
If there's no judgment, this looks like a violation of the electronic funds transfer act. Since they had your account number from the checks you were paying, they could dummy up a check, say that you signed it on the phone, and put it through. Your right to get your money back runs through your own bank. You need to go to your bank and say, "This was not authorized. Get my money back." Then it's your bank's problem.
(Remember when there used to be checks, with signatures, and your bank was supposed to compare the signature on the card with the signature on the check? If the bank doesn't have that, the burden is on the bank if they left money out of your account without your consent.)
Is this company an original creditor--somebody you did business with directly--or a debt collector? If they are a debt collector, you can sue them for taking money without your consent. That's the Fair Debt Collection Practices Act. In some states you could sue an original creditor, too. I don't know about Washington State. Check with a lawyer there who does consumer law.