This number called me on my mobile - didn't leave a voicemail. I tried to call back from my landline but the call wouldn't go through.

No idea what this number is. Never leaves a message and usually only rings for 10secs

This number has been harassing me and is calling every day. Tonight I answered the number but it hung up on me. If it belongs to tell marketers I would like my number to be removed from their list and an apology letter sent for being nuiances!

This number called but I couldn't hear anything, so hung up after 10 seconds or so. Just as I was hanging up, it sounded like a recorded voice started talking, but it was too late to tell.