An Apology After Cancellation of Order Should Be Swift!

Dear

This is to acknowledge receipt of your letter of [date]
in which you set forth your reasons for cancelling your
purchase order #

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

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