US Bank Mistake

I purchased a vehicle in 4/06 and obtained a lease from US Bank. I decided in 3/08 to purchase the vehicle. My bank secured a loan with me and called US Bank for a payoff. Someone at US Bank sent a faxed quote to my bank, my bank sent a check to purchase the vehicle. Now US Bank says they made a mistake and sent the wrong quote. They want more money. My bank tried to talk with US Bank but they don't want to discuss this with them. They have now put this to collections, even though I am making my payments on time to my bank, I am receiving numerous calls from a collection agency who tells me they are reposessing the vehicle this week. US Bank will not take responsibility for their own mistake they are punishing me for their error. I have excellent credit and they are ruining it for me. My suggestion: Tell everyone you know not to deal with this bank and if you do deal with this bank, take your money elsewhere. This corporation doesn't know what "customer service" is all about, I am proof of that.