因為唔係好明你行業內嘅專有名詞, 所以只可好general咁試吓, 希望有其他做你同行嘅媽咪可以提供更多幫助.
For now, let's give it a try.
================
Dear [name],
Thank your for your enquiry about [details of the issue, in your case, shortage label. Should describe on what item].
We are in process investigating the issue/situation and would appreciate if you can provide the following documents to help expedite the process:
1. xxx
2. xxx
3. xxx
We will provide an update to you within [time you feel like you can response with an update or answer, suggest something like 48hr] upon receival for the above mentioned material.
[Customer's company name] is an important customer for [Your company name], we appreciate your business and would prompty response to your request.
Should you have any other question, please feel free to contact us through email or phone [phone number].