After buying a 5N0 module and PnP loom (both from members) I got the chance to fit them this morning. After a simple fitting process and fitting a dash cam at the same time I got round to getting her working.
The problem was she would not recognise my phone or any phone in the house. After much googling without joy I plugged in VCDS and had a look, no previous profiles on there and coding was correct etc. After a sit down and some Dr Pepper I went outside and looked on MFD and checked out the phone options and it turned out it was trying to connect to the previous owner. A quick "cancel" and it found my HTC M8 without issue.
One now has a fully functioning Bluetooth system. I don't need music streaming and will never own an iPhone so the 5N0 is fine for me :)
If anyone is wondering, yes the HTC One M8 is rSAP compatible.