After further investigation it seems some accounts may have been accessed by attackers guessing the password after multiple tries.
Although it is listed as a Connect device, by no means was the Spotiamb player used in the compromise of accounts. The reason why it appears as a Connect device is because someone logged in with that user's credentials.
We recommend resetting your password and disconnecting from all devices using this link. If this does not solve the issue for you we will gladly help out. Send us a message over here then post your case number here.
So I've done what you suggest, deleted all devices (which included a PC laptop that absolutely isn't mine) and changed my password but Spotiamb is still visible on my device list. The message link you supplied throws a 404, so you need to fix that.
Possibly related: this message came up when I logged back into my account on my iPhone. I don't have more than three devices.
Getting a bit spooked by this. Please sort it out. I gave Apple Music a spin but decided to stay with Spotify, couldn't see any compelling reason to change. Beginning to wonder now.