I am writing with
reference to (situation or complaint) on (date). Firstly I
apologize for the inconvenience caused to you by our error/failure.
We would like to
assure you that we take great care to ensure that important matters such as this are
properly managed and processed, although due to (give the broad outline of reason), we
have not succeeded in meeting your expectations.
In light of this,
we have decided to (specify solution/ offer), which we hope will be acceptable to you, and
we also hope that this will provide an opportunity for continuing our relationship.
I will call you
soon to check that this meets with your approval. You may also contact me in case you have
any further cause for concern.