A method of processing a payment instruction including: receiving a payment instruction from a user, the payment instruction including payment details and an electronic signature, the electronic signature being destroyed if the content of payment instruction is altered; checking presence of the electronic signature and confirming integrity of the payment instruction when the electronic signature is present; wherein in event the integrity of the payment instruction is confirmed, the method: i) stores the payment instruction in a first storage unit using a relational database management system (RDBMS); ii) replicates the payment instruction and stores the replicated payment instruction in a second storage unit using the RDBMS; and iii) transmits an acknowledgement signal to the user once the payment instruction has been successfully stored in the first storage unit and the replicated payment instruction has been successfully stored in the second storage unit.