Apology letter can be written against complaint. If anyone make a complaint for anything then the same person needs to apologies for the complaint made. The apology can be verbal or written in this case but if the complaint is formal apology should be in a way of writing. This kind of apology letter address to the person who has made a complaint with his named and address mentioned on it. It should state the reason for which the complaint has made and apology for the same.
Sample apology letter complaint
07 September, 2011
Subject: APOLOGY LETTER IN RESPONSE TO CUSTOMER COMPLAINT
Dear, Mr. Jake
I, Mr. Derek E. Fryer-Customer Relation Manager on behalf of my company Hindustan Unilever Pvt. Ltd sincerely apologies to you. As we receive a notice from your side that you had purchase an expired medicine of our company. We hereby inform you that this was unintentional and the packet of expired medicine was undoubtedly gone along with the unexpired packets. I know if you would have been consume the medicine the result would be dangerous therefore we always advice that please see the date of expiry before consuming any of the products. We are ready to pay to the fine amount mentioned by you in your notice. But we request to you that please don’t take the matter to the consumer court. I hope you will accept our apology and kindly act in favor of us. Hope to hear the needful from your side.