Product: Vehicle loan or lease

I have an account with Santander ( XXXX ) and have had issues with them non stop. 
On XX/XX/XXXX, I entered into an payment agreement to pay only interest on the loan for 6 months so that I can have a lower payment. I paid {$250.00} to start the agreement on XX/XX/XXXX and the payment agreed to begin on XX/XX/XXXX was {$270.00}. On XX/XX/XXXX, I made the first payment of {$270.00}, that day it looks like it was reversed. On XX/XX/XXXX, a payment for {$270.00} was made and a payment was not made for XX/XX/XXXX. In XX/XX/XXXX, my car was repossessed and I was told, in order to recover my car, I had to pay everything except for no more than {$250.00} that would assess to my account on the next statement. I paid a total of {$1900.00} for payments since XXXX  ( is what I am told ) and fees. On XX/XX/XXXX, an unknown fee of {$380.00} was assessed to the account. No one is able to tell me what it is and clearly, it is more than {$250.00}. I was then told that my next payment would not be until XX/XX/XXXX. I also asked repeatedly for a break down of the {$1900.00} paid at the time of repossession. No one can tell me. I was told they should have collected the repo fees against the {$270.00} payment but, they collected the car with the {$450.00} payments instead of the {$270.00} ( an error confirmed by Santander ) so there should be money left over ... but there isn't. Since my payment wasn't due untilXX/XX/XXXX, XX/XX/XXXX ( per the statement {$780.00} was due- {$450.00} payment + {$330.00} ) I made a payment for {$500.00} for XX/XX/XXXX even though I was still supposed to be under the payment of {$270.00}. I received an XXXX statement stating I was due {$1300.00} ( {$450.00} payment + {$830.00} past due???? and {$76.00} in unpaid fees??? ) what are these late fees and past due balance??? On XX/XX/XXXX I made a payment for {$550.00} and called to inquire on this statement and how the credit report was being reported. How could I be past due so much if I am overpaying AND I " had to pay all fees including late fees at the time of the repo ''?? They told me I was up to date and had left over money for my XX/XX/XXXX payment and they were " fixing '' the issue in accounting, not to worry about it. I did not make a XX/XX/XXXX payment. My XX/XX/XXXX statement indicated I still owed {$1100.00} and all kinds of accounting had been done again ... but not to my benefit. I made a XXXX payment for {$450.00} and received three calls as of XX/XX/XXXX to " explain ''. One was a male who explained he would help me, placed me on hold and disconnected after being on hold for a long time. The other two times I XXXX from the executive offices called ( would not give me her employee ID and stated I could not contact the CFPB and didn't even know who that was ) she would not allow me to ask questions and stated I would not be able to speak to anyone else. When I explained they overcharged me when my car was repossessed because they collected payments for {$450.00} and not {$270.00} she agreed and placed me on hold, never to come back. Before she placed me on hold, I explained, they keep assessed fees that no one can explain, I needed a breakdown of where my money went when I paid for the repo {$1900.00} with the payment of {$270.00} plus a break down of the fees assessed to see if there is money left over. And I need an explanation of the fees assessed since I was told they were all included except for {$250.00}. I feel that this company is super shady and is on a mission to reposes my car. I have over paid on my payments and overpaid when my car was repo'ed and they are saying I am still past due ... .and my XX/XX/XXXX payment is {$550.00}. Please HELP!! This company is out of control!! And the reps don't know what is going on and keep telling me different things!!