Writing an official apology letter need not be difficult based on the fact that most businesses pride themselves in keeping a good rapport between suppliers and customers. It is this good naturedness that keeps the company going when it is able to account for its shortcomings and compensate for it for the sake of business confidence.
The letter should always carry the reason that it apologizes for and on behalf of itself for its incapability to honor its side of the agreement and also offer to explain to the recipient as to what the sender intends to do about it. This ensures that whatever confidence that has been hurt by the business’ inability is restored by the wordings that are written in the letter. These should be clear and concise, leaving little to the admission of responsibility, and action to ensure that the error will not happen again. Beating around the bush is never an option and shortness and simplicity should carry the content of the letter.