“RC05 - Do Not Honour”. is a rejection from the issuer side.
Do Not Honor is a generic default bank-generated response description that a customer’s issuing bank is not validating the funds for transfer. The Do Not Honor description is a non-descriptive catch-all code and can occur for a variety of reasons these including incorrect passwords, overseas purchasing restrictions, insufficient funds or incorrect expiry date or due to suspicious behavior, internal risk, or transaction processing parameters.
PayTabs has no control over bank rejection,
Next step: kindly suggest cardholder to coordinate with his/her issuing bank to get more information about the reason for rejection.