A computer-implemented method for facilitating payment of a total amount comprising multiple future instalments by a customer (3), the method comprising: receiving, at an instalment payment server (5), an indication from a mobile device (7) associated with the customer (3) to set up the payment by the multiple future instalments; generating first authorisation data indicative of an authorisation of the multiple future instalments; sending the first authorisation data to a mobile device (7). The method may include displaying on the mobile device (7) an optical machine readable representation of the first authorisation data; and scanning, by a merchant POS system (13) associated with a merchant (11), the optical machine readable representation of the first authorisation data from the mobile device (7). The method also comprise: receiving, by the merchant POS system (13), purchasing data for a purchase of one or more goods or services for the total amount; and sending the purchasing data, merchant data and second authorisation data representing the scanned optical machine readable representation to the instalment payment server (5). The method further comprises: determining, by the instalment payment server (5), the customer (3) based on the second authorisation data; and determining validity of multiple future instalments based on the total amount and the authorisation of the multiple future instalments of the determined customer. Based on determining the validity of multiple future instalments, the method comprises: sending a continuation to the merchant POS system (13) to cause the merchant POS system (13) to generate an indication that the one or more goods or services (21) can be released to the customer (3); and initialing the multiple future instalments at respective points in time.