This process is used when you want to file a report against a merchant through Visa or Mastercard. Examples of reasons include, but aren’t limited to: 

• There was a minimum or maximum purchase amount required to accept a card as payment. 
• There was a required surcharge for the transaction. 
• The business would not accept the card. 
• You were asked for an additional piece of identification. 

Visa  
File through the following site: https://usa.visa.com/Forms/visa-rules.html. Fill out the form with the requested information about yourself and the merchant. Then explain what happened and select “Submit”. 

Mastercard  
Contact them directly, by phone or online. Call 800-622-7747 to speak with an agent or visit https://www.mastercard.us to send an email.  

• When visiting Mastercard’s website, there’s no form to complete. Instead, scroll down the page to locate their “FAQs” page. Then, scroll down and choose “Problems shopping”.  
  See also: Mastercard Frequently Asked Questions. 
• Within this section, there’s information on where to send an email to Mastercard. They also provide detailed information about merchant surcharges and fees.