[AttackHelicopter]

They have always used DHL to ship to me in the UK, no matter how small it was.

Im assuming you signed for it? So DNA isn't an option? Im also assuming its not really light so you couldnt say its empty?

What did you originally say to SE them?

This doesnt help if its already delivered but the driver who delivered to me once put it over my fence,  I claimed it ended up in a bucket of water and ruined it as it was a present. they shipped another out to me.

Yes I did sign for it, and it's not light at all. I told them that there were almost no lego parts left in the box.

The driver delivered it to my hands, so I don't know if I can tell them that it was wet and soaked when delivered. I could however claim that it was dented and damaged inside the cardboard box which could not be used a birthday gift, but it is a very weak excuse in my opinion.

Use the "wrong Item received" method.

Purchase something that's significantly cheaper that they stock. It must weigh the same (or close to It) and when they request the return, send them the wrong Item.

I'm not doubting that this could work, but I rather go for a free extra product because mine weighed around 3kg and there's probably no cheap lego product that weighs the same.