Dear Chayanut,
Please find attached document. For your information, the account discrepancy reason as below:
As the regular price, this order’s amount is USD3717.88. So actually we should rebate 5% plate to you is 46.7 SQM. You can see from attached part of green ,our one package plate (invade,1030*790)is 40.685 SQM, so we have to add another package but the addition SQM, we are calculated as the actual price (USD3.5).
Feel free to contact me if you have any question.