Review loan payment and payoff instructions for auto loans, personal loans, lines of credit, credit cards, and mortgages. A vehicle payment plan agreement is a contract between a buyer and seller of a vehicle that agrees to installment payments.You'll see an option to make your final payment online. You can also mail your payoff payment to: Payment Processing Center P.O. Box 71119. To get a payoff letter, ask your lender for an official payoff statement. Call or write to customer service or make the request online. FAQs: What do I do if I want to return my leased vehicle or buy it out? How do I pay off my financed vehicle? Who is Requesting the Payoff Quote? Vehicle Payoff Sample wholesalers Letter.