Are they being shutdown on google side or spotify side ? If it's google side maybe it's what they are detecting you are using it with. I had some gmail accounts shutdown when I just used it to login to other services with but didn't have any emails or activity on them but just that. Could have been other reasons I lost mine but I'm not sure if it's google shutting yours down or spotify.
About proxies, I was looking into this and the setup I was going to use would basically downloaded the music to prevent high data usage on the proxies, then it would use a mobile proxy that would connect from different cities. Check marketplace for multi-geo mobile proxies.