As my English isn't good enough so you didn't understand correctly, this item was not delivered last time. Therefore, please deduct the amount of this item from the total amount.
I am afraid that you had misunderstanding because of my poor English. Please understand that this article was one which the last shipment lacked, despite the payment. Therefore, the price of this article must be deduted from the total amount.
There seems to be some misunderstanding because of my poor English. This item is what wasn't delivered the previous time. So please deduct this from the total amount.
It looks like there was a mis-communication due to my poor English writing skill. This product was unavailable last time. Therefore, I ask you to please take off the price for this product from the total price.