Touch and go all fits apart from one plug.

Hi all,
I have a 2011 Toyota Prius t4. It came with a standard CD player and also had steering controls for phone operation.
I really wanted the touch screen version so I enquired and was told that if I buy a touch and go it would fit and control the interface using my steering wheel controls. I don't want to use the Nav.
I went ahead and bought a genuine Toyota touch and go unit from another 2011 model.
All fits apart from one plug which is different to my original. The touch version comes on and works fine apart from my steering controls and mic, so defeats the point.
Has anyone else encountered this issue? Is there an adaptor I need to purchase to fit the last plug?
Many thanks