Simply replace the unfilled areas such as "__" and "_[date]_" with your information.
This is to acknowledge that we received your notice whereby you informed us that the goods shipped to you on [date] did not conform to our agreement dated [date].
We apologize for this mistake.
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 look forward to your response.