Audit of loan documentation in banks

That is the least possible scenario to the best of my knowledge, because most of the banks has a practice, that the bank agrees to pay say 80%/85% of the total price of the asset, what banks do is they will take the margin amount(the amount the bank's customer agrees to pay) from the customer and the bank will pay the whole amount to the seller of the asset, also the bank keeps with it  the invoice raised after payment which will show the cost of asset. As you said that the bank manager and the customer might come into an agreement, I think that is not possible unless all the employees have colluded to get mutual benefit