This email is in reference to the order made on date __/__/____ (date) having order ID ________ (mention ID). This is to inform you that we have successfully _________ (processed/delivered/other) your order on date __/__/____ (date) and I am enclosing the invoice for your reference along with this email.
As discussed earlier, the total amount for the order is _______ (amount) and you have made an advance payment of _______ (amount). I sincerely request you to pay the balance payment as soon as possible.
Thank you for doing business with us. I am looking forward for a quick action from your end.
___________ (Contact details)