Lazada have accepted my cancel request, so just waiting for the $$ to arrive back on my card.
Yeah, the whole thing smells of some kind of scam.
Dodgy employee dealing out the back door perhaps?
I'd already decided not to deal with them outside Lazada, there are other (slightly more expensive) purveyors of the same item, so once I get my $$ back we shall see if they also have a weight issue.