Format the letter in a formal template. If you don't know the correct formatting for a business letter, use one of the available templates through your word processing programs. Send the letter to the attention of "Billing Inquiries."
Keep your letter of dispute brief. Get to the point quickly and try to keep the letter no more than a page long. Give the date of the bill, your account number and the reason you should not have to pay the charge.
Tell the billing company what you want them to do to rectify the situation. For example, you may want to write something like, "I expect the charges to be removed from my account along with any related finance fees."
Give your contact information. Before your closing, include a daytime phone number and alternate numbers in order for the company to reach you to discuss the dispute.
Make a copy of the letter and the bill. Keep a copy of the letter along with your billing records from the company. Include a copy of the bill with the letter prior to mailing out the document.