I believe I have resolved the ongoing rattle I've been experiencing, I didn't resolve this earlier as the continuing bongs far outweighed a minor rattle, anyway the source of the rattle might be helpful to others.
The rattle was coming from a small plastic clip at the end of the slider rail for the front passenger seat, the piece of plastic was slightly loose so a strategically place piece of paper has stopped this irritation, accessible from the rear door, the piece of plastic is at the very rear of the slider rail.
Oh and another thing, the undertray (part of the current recall) was also replaced last week when they changed my steering wheel.