Santander Consumer USA Inc. Payoff balance error? Dallas, Texas

On or around February 16, 2012 I contacted Santander's customer help line to determine the payoff balance for my auto loan as of February 29, 2012.  When I received the amount from the automated system, I was surprised that the amount was higher than expected.  So, I used the option to speak with an account representative.  The account representative confirmed the payoff amount.

On February 24, 2012 I paid the balance due as quoted by Santander's system and by their account representative.  On February 27, 2012, Santander sent me a letter saying I owed an additional amount.

When this loan was owned by CitiFinancial I was able to use an amortization table and tie, to the penny, with my CitiFinancial statements.  Since the loan was purchased by Santander, I was never able to tie between the amortization table and the Santander statements. I was never able to get a satisfactory answer for the differences, since the majority of the account representatives are not accountants.  In addition, I notice several payments that were applied to my account 1 - 2 days after the payment was electronically withdrawn from my bank account.

I am now putting up a fight on the additional amount Santander says I owe.  While the amount is small and I would probably save the heartache by paying it, I am REALLY tired of Santander billing and payment application errors.