A dispute (also known as a chargeback) occurs when one a cardholder questions your payment with their card issuer. The issuer creates a formal dispute which immediately reverses the payment.
Each Acquirer has their own dispute resolution process through which you can respond and submit evidence to make your case that the payment was valid. If the dispute is found in your favour, the disputed amount and fee is returned back to you. If a dispute is upheld, the card issuer’s decision is final and the cardholder’s payment remains refunded.