If you have received a chargeback on a POS transaction that you cannot defend in the Adyen Customer Area, it is most likely due to a fraudulent reason code.
In addition to the fraudulent reason code, please check the POS entry mode. If it states Manual entry it is difficult to challenge the chargeback. This is because Manual entry is a risky method of processing the transaction, as the cardholder is not verified through chip and pin or magnetic stripe and pin. It immediately makes you liable for the chargeback and we recommend to offer it only for exclusive shoppers that you have verified thoroughly and who have a longstanding purchase history.