I have a purchase order of 10 items each 10$. I got the purchase invoice from the vendor and post it. But later he send and notes that the price is 9$ and send a debit note stating that for the received 10 items (I will not return any of them) but for each -1$ is to be adjusted in the price. So how to post a debit note adjusting only the price/amount and not affecting quantities but only the price and total due amount to the vendor?