A)  The RTP network is a final, irrevocable, credit push payment system. This means once the payment is accepted, the payment cannot be cancelled, reversed or recalled. However, this does not mean the Sender can't do anything. According to the RTP Operating Rules, a Sending Participant may initiate a Request for Return of Funds (non-payment message) to the Receiver for any reason, including a request of funds related to an unauthorized or erroneous RTP Payment such as wrong receiver. Once a Request for Return of Funds is received, the Receiving Participant must respond within 10 banking days of receiving the request except for messages sent due to fraud claims or breach of warranties. In those cases, the Receiving Participant may take longer than 10 banking days to respond in order to complete its investigation. The response to a Request for Return Funds message is either negative (indicating the Receiving Participant will not return the funds) or positive (indicating the Receiving Participant will return the funds). Once the Receiving Participant has sent their response, the Sending Participants may not resubmit a Request for Return of Funds for the same payment.

A Request for Return of Funds is a just that - a request. The Receiving Participant is under no obligation to "return" the funds, which is why Senders should carefully review all RTP transactions before pushing send! If the Receiving Participant decides to return the funds, it may initiate a payment message that sends the funds (as a credit push) to the original Sender.

Source: RTP Operating Rules (Section VII.D)