Dear
As I received your letter on (date) with my check attached marked “insufficient funds” dated (date), I called my bank at that very moment.
The executive I spoke with, (name), discovered that for some unnecessary reasons the bank had failed to credit my account with a substantial deposit I had already made several days prior in my account.
As per the talks with the bank, they have assured me that they will be sending you a formal letter of apology for the mistake on their part. Attached is my check in the amount of $ to replace the dishonored one you have returned.
I regret for the inconvenience caused to you. Thank you for your cooperation.
Apology to Receiver of NSF Check