Hi all, I am wondering if anyone else has had issues installing a 3rd party replacement radio upgrade?

I purchased a Pioneer SPH-DA130DAB Multimedia player to fit into my 2011 FL2 SD4 GS.

In order to do this I bought a replacement Bezel along with a "Connects2" upgrade kit
This comprises an MOST amp retention Interface ( my vehicle has the Alpine System running on a MOST 2 fibre optic Network) and a steering wheel function interface.
My vehicle does not have the Touch Screen Nav system fitted above the main Radio console.

Installation should be a simple case of removing the factory fitted radio and CD player,
Connecting the Fibre optic connector into the new interface which is fed audio from the RCA sockets on the new head unit.
There is a second fibre optic which is plugged into the Radio Fascia which is replaced with a simple Bypass loop.

Unfortunately, although everything powers up ok and the head unit appears to be playing, no sound can be heard.
Even the steering wheel functions are retained.

I contacted the seller and was advised that I needed to disconnect the Bluetooth Phone module in the boot and fit a second fibre optic Bypass loop? this still isn't working so am now at a loss as to what to try next?