Thanks for the reply, it is a bit strange as it was working but has developed a fault whilst not being used,which is why the dirty switch contacts made sense.
I removed the top of the battery and sprayed switch cleaner over the switch area and checked the fuse,which was ok.
The problem is ebike battery companies just want to rebuild the battery with new cells and do not want to get involved with the control unit.
I purchased the bike direct from Leon cycles with a one year warranty on the battery,which has now expired,, but it is easier to contact the Pope than them.