Reason:
1.) We have understood that you have accepted for the price.
2.) You required for discount but we could not because
2.1) Regard to No.1 in above
2.2) Job had been done. Besides, we had paid for all labor cost and tools already.
2.3) You have requested discount but we could not. So, you requested for breakdown cost.
Then we did submitted you promptly.
We did really gave you our best price.
In regard of discount, please also kindly request again for next time with next item.
For us, we will do job after we get your Purchase Order from next time in order to prevent this inconvenience.
Your understanding will be highly appreciated.