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.