What a relief - i finally found a Snapshot that was not damaged, & thus have managed to roll-back to it, then perform the usual
sudo zypper dup --no-allow-vendor-change
to become TW 20170703 [it was on 20170630 when last night’s mess occurred]. All seems ok now, phew, so maybe tomorrow i’ll have time to dive back into this thread & try the actions you suggested / answer your questions. I appreciate your help, thanks.