Well, well, well... I don't know about other territories but, in the UK, that's some SERIOUS customer service...
I wasn't really expecting a reply, but...
They've got back to me already (less than 48Hrs). They've explained that they have changed the plastics used on these stands some time ago, that the new stands do not have the same issue, and that they will replace old stands free of charge.
That is seriously impressive in my book. As one of our sales guys here at work said "way to keep a customer!!"
I'll be ordering the extra two I'd noticed I needed over the last few months! (I've run out of walls that I'm allowed to put wall-hangers on!)