Dear

This is to acknowledge that we are in receipt of your
notice whereby you informed us that the goods shipped to
you on [date] did not conform to our agreement dated
[date].

We regret this unintentional mistake on our part, the
reasons for which were [explanation]

While we recognize that the time for performing under this
agreement has expired, we are requesting that you extend
the time to [date] in order that we may cure the
defect by replacing the shipment with goods that conform
to our agreement.

Please accept our apology for this inconvenience. We will
be looking forward to your response.