What I would imagine is that spotify updated but Volvo hasn't got around to patching their version of the client yet or they just botched the patch files or the path to the correct files in the download centre.
Let's hope they don't take 6 months to fix it again
Any chance you could share contact info of the representative you contacted with for future reference? Most Volvo customer supporters appear to go with their default answer of "contact your local dealership" for pretty much every problem.
Yesterday I was able to install the app again and it looks like it's working fine for now. The app was still showing as 0.00mb but the download took some time to finish and the install went through normally. Since I'm in Brazil, I don't know if the server is local or global, but here it seems like the problem was solved!
Have been able to download and install despite showing 0.00MB (just took 30sec) - entering the code using Spotify.com/pair - connected to India (as mentioned in a previous post) - all working fine including my library.