Well, I've had a phone call this morning from a lovely man called Jon in the Rocks IT Dept, presumably having read this thread.
He's told me there were a few problems with this design, a higher failure rate than usual. So even though it's out of warranty, if I send it back they'll try to get it repaired for me.
I'm soooo impressed by this level of CS, and thrilled that I might well be having my lovely bangle back to its blingy best soon.
So thanks to all at Rocks, especially Jon (and of course to all my lovely bling buddies for sympathy!) - I love that they cared enough to contact me!
xxxx