No-one seemed able to help,so I have lived with it but it has been a pain because of tandem seating.
Some one on one of the stands at splash suggested trying ferrite rings.
I bought 4 little snazzy ones from Maplins that are in little plastic cases that fold over the cables on the headsets and snap shut.( I am not sure if you need one on each lead or just on the phones but I put one on each anyway--less tham £10) and ..hey presto... Perfection.
If your intercomm is a bit dodgy..give it a try!
