Macdee Duo Compact?

Ive just installed one of these cisterns and yep it keeps running on after a 6 ltr flush. Ive spoke to the technical dept who have advised that the blue cable needs re routing as its not releasing the cable if it has a slight bend in it. My problem is that ive used reduced depth units and have no other option other than the way the cable is run. I still think its a syphon fault. Anyone got any ideas??