$20k for any individual or group that provides me with a working system for controlling the balance of my pre-pay oyster card. Source code for the hack and instructions for suitable hardware required.

The Oyster system is an RFID based cashless travel card. Cards can be purchased annonymously, and the card itself contains the balance. I want a way to control the balance on the card so that I may correct it when "errors" occur.

I will also award partial payments to any who provide information that furthers the development of a working solution. The money has been deposited and is held in escrow.