There are two possible reasons for this:
1. The refund and chargeback were exercised around the same date and crossed each other.
2. The issuing bank did not check the refund record before exercising the chargeback.
To avoid chargebacks, inform shoppers that you issued a refund and communicate the date, the amount, and the ARN number of the refund to the shopper.
For E-commerce credit card payments for Visa and MC, you can download a ‘Refund Letter’ from the Adyen Customer Area and send this to the shopper.
If the refund will be issued on a future date, we recommend to clearly communicate the timeframe to the shopper.
Adyen has enabled automated defense on fully refunded chargebacks for Visa and MC, which means that the chargeback will be automatically defended and reversed. You should defend transactions that are partially refunded.