Dension BT Gateway - audio cuts out Handsfree & music

[Diamond Hell]

Having run a VCDS scan on the car with the EPB recently I noticed a radio fault:

Address 56: Radio Labels: 1K0-035-1xx-56.lbl
Part No: 1K0 035 186 P
Component: Radio BVX 016 0023
Coding: 0020200
Shop #: WSC 00066 000 00000
VCID: 336571FA52BCD3A6B3-8066

1 Fault Found:
01044 - Control Module Incorrectly Coded
000 - -

Since I got the car I have added in a Dension BT Gateway Lite. I returned the first one, as it was cutting out both in the Passat and also in the T5 we have. The replacement unit still does the same.

On the basis that there appears to be an incorrect coding on the stereo (RCD300) do I need to make a change to the coding to make the Dension work correctly?

Any assistance would be much appreciated as I can't safely use it for handsfree at the moment, because it randomly just cuts out, leaving neither party hearing anything, but it doesn't drop the callwhich is particularly unhelpful!