How to Solve the problem between customer

If there are some issue about quality during the production, do not tell with customer the ture reason, I write as belor for your guys referene, hope I can get more different suggestions.
Dear xxx：We would like to update you regarding the production of the bags/rolls.
The bags/rolls have been completed successfully. However, there was unexpected thing happened during the production process, the material loss was too higher, which resulted in the final completed quantity is 12,730 pcs. We sincerely apologize for the inconvenience caused.
Please kindly let us know whether you would like us to arrange the balance quantity for you. If yes, we will prioritize the production schedule and check the soonest completion time accordingly.
If needed, we can also arrange shipment of the finished quantity first.