I have had problems during sveral trips in my 2007 Bessacarr E560 motorhome with the Fiat Ducato 2.3 multijet diesel engine stopping suddenly as if switched off. Luckily it always re-started OK but very dangerous as the power steering and brakes disappear!I spent a lot of time and money trying to find and repair the problem but nothing worked. I read on the forums that many people had had the same problem and learned there had been a re-call by Fiat due to a faulty ignition switch problem.I was investigating this when the switch failed completely. I removed it and ordered a new one but when it arrived it had a different steering column diameter of 41mm. The old one is 47mm. I had entered all the requested vehicle details but still got the wrong part. After visiting several parts suppliers sites I found there are several versions of this switch, some with 5 pins some with 7 all offered for the same vehicle details but there are no comments on the steering column size.Can anyone help and tell me how to identify tand order he correct part please?