Dear ____________ (name)

This is to acknowledge receipt of your letter of ____________ (date)in which you set forth your reasons for cancelling your purchase order number __________

I am very sorry about the misunderstanding that led to this cancellation and has been taken up the matter to the management in order to ensure that a problem of this nature does not occur again.

As one of our valued customers, your satisfaction is our primary concern. Please accept our apology.