[mothered]

Is there a need for the weights to be exact or is it a matter around about that weight?

Some carriers round up the weight to the nearest figure, so It doesn't have to be exact.

As close as possible will suffice.

Therefore it would be a pretty much fool proof method unless they state they have cctv footage etc?

As long as they stock the wrong Item, you can't really go wrong.

Pickers make errors "every day", some more than others and every warehouse Is aware of this- which further supports your claim. They're not going to do a stock take for one Item, hence they have very little grounds to decline It.