6000Cd - Installed Ipod Adapter Cable But No Control, Only Audio/charging. Disable Aux Input?

So I bought one of these iPod cable adapter kits from Connects 2. It's one of these cables that allows you to trick your radio into thinking that your iPod is actually the CD changer, so it streams audio through the head unit whilst also supplying power to charge your iPod and also letting you send commands to skip next/previous track, shuffle and repeat, and also select playlists all from the buttons on your standard Ford radio (a 6000CD in my case).

Unfortunately, after installing it I am only getting audio passed through/power supplied to my iPod. I've tried several models of iPod, iPhone etc and none of them can be controlled from the radio head unit as promised on the website. The guys at Connects 2 reckon it's because my Fiesta already has the Aux input port for connecting MP3 players etc, but I can't see how that would stop the CD changer from sending commands to the iPod....

I've seen it working fine with the head unit buttons controlling the iPod in videos of the same 6000CD head unit online, so I know that it is possible. I also know that certain models of Fiesta were released with the ability to have the Aux port added but not actually activated, so I'm wondering if there's a way to disable the Aux feature and if that would allow me to use the head unit buttons as promised.

Anybody know anything about this stuff or know anybody who might??