Just bought a tow bar for my 2006 307 se. But was told by the fella that from 2005 onwards I need to buy a 'smartbox' at the cost of £50 extra to run it? Anyone have this problem? ATM i have the towbar and standard wiring kit but dont wanna fit it unless i know for sure it will work or should i pay the extra £50. My mechanic doesnt know if the wiring has changed in the 307 from 05