Raise credit card dispute

I win a credit card dispute today. Some restaurant in San Francisco charged me twice for one meal. The second charge is small enough to make me hesitate for a while before I raised the dispute over a phone call.

When and how I should wield the dispute weapon?

• Unauthorized use of my card. Under the law, I can not be charged for more than $50. I should call credit card company as soon as I noticed the unauthorized use.
• Disputes about how much I owe. I must write (phone call also worked for me) to the credit card company within sixty days of the first bill with the improper charge. I must include the following information:
• my name and account number
  
• The dollar amount I dispute
  
• Information as to when it was charged and the name of the merchant.
  
• A statement of the reason for my dispute.
  

A special case is dispute about problem with the quality of goods and services.

• I must have made a good faith effort first to resolve the issue with the merchant directly.
• Enclose the letter which I wrote directly to the merchant.
  

What will happen?
The credit card company is required to investigate.

• In many cases, the charge as well as interest associated will be canceled.
  
• Until the dispute is resolved, I need not pay the disputed portion of my bill.

Indiana government provides useful information and a sample letter here.