Heres the latest from the dealer after some investigation:The final drive hasn't actually failed.It was discovered that there has been an ingress of water into the FD.The total mixture of oil and water was 400ml which is double the recommended oil capacity.You cannot overfil the FD with oil because the filler hole is in the horazontal plane so excess oil would pour out.The only possible access point for the offending water is through the breather,hence Joe Duffy BMW of Dublin are totally exonerated,I apologise unreservidly to J.D. BMW for my assumptions.Twice the same fault has manifested itself(5000 mls and 11000+ mls) I wash the bike thoroughly on a weekly basis but would state that I'm not overzealous with the hose.When the extra fluid is ejected from the FD it covers the rear tyre rendering the bike dangerous.The ingress of water must be small but over a period of time eventually exceeds the FD capacity.The bike is due a 12000 mile service soon so the dealer will check FD for water ingress.I think the breather should be designed so that no ingress of water is possible.The dealer did not charge me for the investigative work that was carried out and there service proved to be beyond reproach.Thanks to BMW Newtonabbey.