Have you tried searching for the song in the Sonos app, playing the song using the same music service, and giving it a thumbs up?

How can I search for the song? It always played in a specific Pandora station.

I have quite a few Pandora stations that I listen to and I want this song back in a specific station.

On the Now Playing screen in the Sonos app, if you tap the Queue icon on the top right corner of the screen, is the song listed?

You could also “un-thumb” the song directly from the Pandora app by following the steps in this link:

https://community.pandora.com/t5/Desktop/Desktop-How-to-Remove-Accidental-Thumbs-Down/td-p/92394

Your answers have been very helpful. Yes I was able to find the song in the thumbs down list, but I am not a premium subscriber, just Pandora Plus, and the system will not allow me to “un thumb” the song. Their website suggests simply deleting the song in the thumbs down list, but I’m afraid that will delete the song altogether. I’ve reached out to Pandora directly for support, but have not yet heard back from them. 

And I’m also seeing two different prices to upgrade to Premium. Their site says it’s $9.99/month, but the app says it is $12.99/month. I’ve also asked them about this price variance but again, no response yet.

The price difference is likely the 30% “Apple tax”, buy on the web site to avoid it.