A transaction processing system for sending user information data to a personal device, and an associated method are provided. The system comprises: a personal device, such as a balance display card; an interface device, such as a card reader for transmitting data to and from the card; a communications network connecting to the interface device; an issuer processor connected to the communications network; and a trusted network processor (TNP) processor connected to the communications network, interposed between the interface device and the issuer processor. The TNP processor is arranged to receive a transaction request message from a card user and to transmit a response message back to the personal device, the response message typically being a transaction authorization together with information for display on the card. The TNP processor is arranged to identify, dependent on properties of the transaction request message, whether the associated response message will require data to be sent to the user information device, and if so identified, to: route the transaction request message to the issuer processor using a standard message; receive the required data from the issuer processor using another standard message; match the received required data to the original request; generate an appropriate response message and script containing the required data; and transmit the response message back to the personal device thereby making the required information known to the user.