First of all you should make sure that you are addressing the right person. For this, you may call the company or visit their website. Talk to human resource department and ask them about the person who handles such issues. You should also request them to provide you the complete address of their office.
Follow the proper format while drafting your letter. Put the receiver’s address in the top left corner of the page. Mention the person’s full name and the designation, followed by the date on which you are sending this letter. Be careful while putting the date as it will be helpful in case of any dispute.
After mentioning the address, you should open your letter with proper salutation. The most common and acceptable way to address any person is to write “Dear” followed by his/her last name. If you are not addressing the individual then the appropriate greeting will be “To whom it may concern”.
After the greeting, you will start the main body of the letter with a couple of courteous sentences in which you will commend their professionalism as an organisation. However, you should not drag the opening as the reader will lose the interest.
Use the next paragraph to describe the purpose of your letter. Don’t try to play with words rather you should be concise and to the point.
If it is a complaint letter then you should give the impression that you still trust the other party and expect an immediate action to resolve the issue. Summarise your letter in a couple of sentences.
Close your letter with courteous greeting like “Sincerely yours” or “Yours truly” followed by your name and address.
Do not forget to write the return address on the envelope and dispatch through a certified mail service.