Right, finally got my motor back from the local stealership...... While I was there, I asked the service manager about the OBDII socket issue and also mentioned the fuse..... His response was, some cars have fuse 130 others have 131, there may be cars that have both, all depends upon the age of the car and variation of e70....... the reason why the "snap-on" computer wouldn't connect to the car was likely to be because the software in the car has been designed to prevent people from cloning key information, so only computers who have the correct software pass keys etc will connect properly...... my cynical mind translated it as, only companies who have paid BMW for the licences so that their equipment will work.
My code reader, on the other hand, is just that, so isn't able to effect the software and carry out sophisticated operations such as cloning etc, so it can do what it does without any problem....... all seems plausible to me.