Since you are not ready to solve this problem and insist on all of us to talk to our banks to solve a problem which is only occurring in case of Spotify, I guess you mean that there is no point in hoping any improvement from your side.
If any time you feel that a number of subscribers can help your business, try doing what Apple Music and Netflix does so that we are actually able to pay them.
I first tried to upgrade to premium with my classic sbi MasterCard. It didn't work. Just because of Spotify I ordered another gold sbi MasterCard so that I can do international payments. Even after that, the issue is the same. I loved Spotify and I had made a lot of awesome playlists here. But, I have no choice rather than stop using Spotify and find some other app until the issue gets fixed. I can't bear that man saying "You know the funniest thing happened last night?".