A complaint letter should be precise, mentioning the nature of the grievance. When you are writing a complaint letter give a clear account of your problem and ask politely to take an action for it.
Here is a sample complaint letter to bank:
Mayfield Appt #20,
Mr. Mark Rich,
The Urban Cooperative Society Bank,
21st May, 2010
Ref: Complaint letter
I would like to bring it to your notice that I have opened an account of mine on the 5th of this month in your bank. Your staff has informed me that I shall get my bank ID, my passbook and cheque book within 2 days. Besides I was promised that I shall also get my ATM card along with them. But with regret I would like to inform you that I have, till date received none of the above.
Since I have shifted here from Chicago a few weeks back, I am finding it difficult to survive without my cheque book and ATM card. I hope you can understand without the bank account how difficult it is for someone to maintain the things in a new city. I need to pay my bills and have to purchase a lot of things for my house but unless I do not have a cheque book here, I can’t do anything.
Thus I request you to kindly look into the matter and issue me all the above mentioned documents and card. My account number is 160925.
I hope you will entertain my problem on prior basis.