Due to the current Covid situation, I've not worried about trying to get Spotify back. BMW have not responded which is understandable and I had resigned myself to probably needing to pay in order that Spotify could be restored.
However, I've just noticed that BMW UK have now added more information
here. The page now clearly states that Spotify is part of Connected Music, but at the bottom of the page in the FAQs, in response to the question "How much does Connected Music cost?", the reply is:
"All new BMW vehicles capable of using this service feature a 3 year subscription from the point the vehicle leave the factory. More details will be announced on renewal costs in 2021 when the first vehicles will start to see this service expire."
That infers that all G20 UK 3 Series should have Connected Music for 3 years. The page also states that cars need software 07/19 or higher (which my car does have). I guess that it will mean a trip to the dealer once the situation improves.
In the great scheme of things, it is not important but the page does now add some clarity to the ongoing Spotify debate.