Help needed if any can.

Had my saff since oct When i got it noticed horn wasnt working only to find the wires had been disconnected off back of horns, reconnected bingo all good, a few ddays after on a nice warn sunny day sat in a pub with the wife and hears an horn a few mins after stuck my head round corner and it was mine, i took boss off (rs 4 spoke) disconnected wires and it still carried on so under bumper i go, I have checked all wiring reconnected and all has been well until just now some 7 months later a nice warm day its done same again.
Has anyone had the same problem or any ideas as to what it could be.

Daz.