I had the same problem on a Givi box where the key snapped off in the lock. Tried tweezers without success then as last resort put a tiny spot of superglue on the end of the broken key and carefully pushed against the broken bit within the lock. Gave it 30 seconds or so to bond and withdrew the key carefully. Worked a treat.
beginning to sound like a christo t thread
Since the box is open, remove the barrell and replace it. It is only held in with a clip. Loads of them on ebay for a tennerhttp://www.ebay.co.uk/sch/i.html?_trksid=p1722.m570.l1313.TR0.TRC0.Xgivi+barrel&_nkw=givi+barrel&_sacat=0&_from=R40Not sure about the Givi but most have a hole at the rear of the lock and you can push the key out.