1. Member States shall ensure that a payer is entitled to a refund from the payment service provider of an authorised payment transaction which was initiated by or through a payee and which has already been executed, if both of the following conditions are met:

(a) the authorisation did not specify the exact amount of the payment transaction when the authorisation was made;

(b) the amount of the payment transaction exceeded the amount the payer could reasonably have expected taking into account the previous spending pattern, the conditions in the framework contract and relevant circumstances of the case.

At the payment service provider's request, the payer shall bear the burden of proving such conditions are met.

The refund shall consist of the full amount of the executed payment transaction. The credit value date for the payer's payment account shall be no later than the date the amount was debited.