I don't know what state you are in, but in Illinois the bank by law has to provide you with a calculation of deficiency. We are battling the bank for the same thing. Had a truck repo'd was worth 15K, owed 15K, they sold it for 8K and now say we owe 6800. I want to know how and they keep denying any information saying it's confidential bank information. Write a letter of complaint to whatever agency oversee's this bank and look under your state's statutes for what the bank is liable for and what they have to provide by law.