Update time. On Monday afternoon/evening I crawled the car up to my local (trusted) garage and asked them to pop it on the ramp so's l could check underneath. Sure enough, offside rear airbag not only badly out of shape but not even located on it's top spline mount. Replacement has arrived a.dyself and bro will have a go at it Thu, plus he has the software to set it up afterwards. Will let you all know how it goes....I might add that I'm saving up to buy the nearside replacement just in case.