Prestige Payment Systems Fraudulent billing practices Vancouver, Washington

I discontinued using their service on July 3rd of this year. They billed me for all of July for the full amount, no pro rating. They then billed me for all of August for the full amount which I only found out in the beginning of September since the ABT fee comes out on one's statement the following month. Now they intend to bill me for all of September's fee ($90) since it wasn't till September 9th that I notified them in writing of termination. I realize that my company might have had some initial responsibility in that we did not notify them on the date of conversion to a new processor but their inability to pro-rate charges to a lesser more reasonable charge seems like fraudulent business practice.