With due respect to state that, this letter is to inform you that we are unable to make delivery on the above referenced purchase order for the (date…) indicated.
We should have our merchandise (business matter) able to ship (name of transport way) within (number of) days in the original delivery (date…) and we hope that you can hold off until that time.
We want to let you know this delay as soon we were advised in order to give you as much time as possible to help to make alternate arrangements, if you needed. We can give surety to you, however, if your order remains in force we will expedite delivery to you as soon as we have received the product or service.
Please accept our regret because of this delay and thank you for patience.
Designation with signature…