How do you revoke a creditors right to ACH debit your checking account? Don't account holders have rights too?

All I want to do it force Cash Call to deal with me directly and stop costing me money in fees with my bank. I want to revoke their authorization. Do you have to do it on the creditor end and bank end as well, or do you just need to revoke it from the creditor and what is the best way to go about that. I'm talking about Cash Call specifically. Any help or suggestions is greatly appreciated. Thank you!