Have you tried a simple reboot of your router? Or contacting the Kiss folks directly, since they maintain the server that Sonos points to?

 I would also recommend that you submit a system diagnostic within 10 minutes of recreating this problem, and call Sonos Support to discuss it, or post the diagnostic number here for a Community Moderator to pick up.

There may be information included in the diagnostic that will help Sonos pinpoint the issue and help you find a solution.

When you speak directly to the phone folks, there are more options available beyond just the diagnostic analysis. 

I finally got round to talking to the them today but they have just said its a regional limitation… i did read somewhere about international stations being stopped because of rights but can’t see why this would affect a UK station in the UK… doesn’t add up to me.

I’ve found a work around for this if anyone else has similar problems.

I was able to find the stream URL from the player they have on the KISS / Planet Radio website and then manually add a radio station to SONOS.

Now under Tunein and and My Radio Stations I have the station and it works.

Same problem here. Feels very strange. 
would prefer to do it through the stations rather than airplay. 

Hi @Jamieswalton.

Thanks for reaching out, we’d be glad to help.

Have you gone through the suggested workaround above?

You may check this article that will provide you the steps on how to manually Add an Internet radio station to Sonos.

For more details please refer to this thread:

https://en.community.sonos.com/music-services-and-sources-228994/tunein-not-playing-stored-favourites-or-many-radion-broadcasts-6847978

Let us know how it goes with the advice above and if you have any questions feel free to reach out.