Call the customer service number on the back of your Visa card. The number will be for the bank, credit union or accredited financial institution that issued the card. Follow the prompts from the automated system to reach a customer service representative. The representative will verify your identity by requesting personal information and/or an account password.
Tell the representative that you want to dispute a transaction. The representative will need the specifics of the problem with the product or service as well as any additional information, such as a receipt number. You may be issued a provisional credit for the charge while the issuer conducts an investigation.
Write a letter to the issuer with details of the transaction and copies of evidence that could help your case. Receipts, shipping labels and any proof that you tried to get a refund from the merchant can help your case. Mail the letter to the issuer as soon as possible to help with the investigation.