Thanks Dave, I know that there is no external microphone installed in the aux port on the back of the stereo, as I confirmed this with the supplier I bought the Vellfire from. I, rather stupidly, assumed that whatever system they installed would be compatible with the system in the van. and that the van would have a microphone installed because of having the steering wheel controls. Can you recommend a microphone that could be used? There seems to be quite a few from brands I have never heard of, so unsure what would be any good. I know the stereo requires some of the dash to be removed in order to pull it out, not something I have done before, so perhaps once I get a microphone, I will have to find someone to install it for me, unless there are any videos available on how I can do this myself? Would need to check the internet I think.
They said that no one has ever complained about this not working before, but that does not mean anything really I would need to find out the make / model of the stereo to see if I can find this out regarding CANBUS. I can get around it, as using Siri on the iPhone will be ok, but it obviously will not go through the speakers.