Where a payment service user denies having authorised a payment transaction which has been executed, or claims that the payment transaction has not been executed correctly, and the payment order is initiated through a payment service provider providing a payment initiation service at the request of the payer, it shall be for that payment service provider to prove that the payment order has been received by the payment service provider managing the payer’s account and that, as far as it is concerned, the payment transaction has been authenticated and duly recorded and properly executed that it has not been affected by any technical or other deficiency in connection with either the service it provides or the non-execution, defective execution or late execution of the transaction.