To be clear I always have "download over cellular" turned OFF.
When I cleared my app data to resolve the "your Pandora session timed out" message my offline stations downloaded while I was not connected to WiFi, this used 1/2 a gig of data (500Mb) in like 20 minutes. I got a warning that I was using too much data and saw that all four stations had downloaded. I checked that I had "download over cellular" off and I did.
Things like this are why people dislike pandora over Spotify and other platforms.
Sorry to hear that happened. I checked in with our device team about this setting for you. By default, we will only download your offline stations over WiFi. In the meantime, I've shared your experience with our engineering team so that they can look into this.
Would you mind providing more details about your device so that I can pass this along on your behalf?
Android version (Settings > About Phone):
Go toProfile,then selectSettings. Scroll to the bottom of the screen for the version number.