View the list of Sample Business Letters Apology to Receiver of NSF Check Disclaimer: Be aware that some of these sample letters have legal, financial, or other implications. If you are not sure about the use of any letter, consult with an appropriate professional first. Apology to Receiver of NSF Check Dear When I received your letter of (date) with my check attached marked "insufficient funds", I called my bank immediately. The gentleman I spoke with, (name) , discovered that the bank had failed to credit my account with a substantial deposit I had made several days prior. The bank has assured me that they will be sending you a formal letter of apology for their error. Attached is my check in the amount of $ to replace the dishonored one you have returned.