[mothered]

They replyed again repeating the same thing of the last email of some day ago.
That they received the wrong item

I'm not surprised one bit.

That's why I've stated this:

Why did you return bottles of water?

I've previously stated here that It should not be done.

Personally, I wouldn't add water bottles.

Unless they're half-asleep on the job, they'd simply say you've returned Incorrect goods.

But you were adamant with this:

The sense would be that someone stole the item e put something else inside (for the weight). Bottles are the more common thing around.

Can you see why It's paramount to formulate your method on realistic grounds?