A system comprises a client module installed on a vending machine, the vending machine displaying one or more items for purchase in a first arrangement, and a purchase fulfilment subsystem. A QR code is generated by the purchase fulfilment subsystem and transmitted to the client module. A first set of signals to initiate a transaction is transmitted by the user device to the purchase fulfilment system. The purchase fulfilment subsystem transmits to the user device a second set of signals to display elements in a second arrangement. The user device transmits a third set of signals to the purchase fulfilment subsystem related to activation of an element. The purchase fulfilment subsystem transmits to the client module a fourth set of signals comprising commands to enable the vending machine to dispense an item. The client module sends one or more instructions to the vending machine to dispense the item.