Mid Atlantic Finance Co double ACH charge on my checking account, charging addittional payment Internet

I bought a vehicle from a local dealer back in october 2012.  I had set up automatic payments with them since day 1.  I was never late on a payment or missed a payment.  Well, this dealer closed and sold my loan to mid atlantic finance co. had I known this would happen I would have never bought the car in the first place.  Mid atlantic finance is the WORST finance company out there.  Early June I get three letters from Mid atlantic finance co. It was a payment booklet, insurance verification and general info and disclosures.  When I got my loan I got it for 30 payments and the booklet was continuing in that sequence with my next payment being in june, nothing changed which was ok.  I was not happy that they charge $6 to make a payment online via ACH or you can mail in your payment which I find quite inconvenient.  Anyways, my payment was due on the 22nd so I decided to make my payment on the 21st which was a friday authorizing for the payment plus their 6 dollar fee.  Next day I loggin to check and its showing I still owe money.  I call to check what was going on and the lady said that I was due for double the amount my payment was.  She stated she was showing two payments coming in and that I should check back on monday or tuesday with them once the payment posted.  I told her I had only submitted one payment which was what was due and also mentioned to her my loan had been sold to them and this was my first paymet.  She stated maybe the other payment was coming from the dealer I bought the car from.  Anyways, her not being able to fully answer my questions and help me, which by the way, she was a little rude, made me feel uncomfortable and knew something was wrong. Today I had the money for my payment deducted from my account for $306.26 (including $6 fee) and a second ACH for $300.26 which I only authorized for one which I owed.  Now my checking account is overdrawn and my bank charged me for the overdraft.  I am very unhappy with their service and bad business practices.  Taking money from your account without your concent is stealing.  I will dispute the second ACH with my financial institution tomorrow and call mid atlantic finance to see what is going on and what I can get resolved or if I can get some type of resolution from them.  This company has very bad reviews online and it seems like a they're a nightmare.  I will try to refinance my loan with my Credit Union and try to stay away from this company.