City under the ground

[RedArrow]

I think there is a problem. Someone has made a city under the place where Redcliffe was. My warehouse is still there. The first problem is that someone has been there. Now he stole 8 diamond pickaxes and 2 diamond swords. The second problem is that I have claimed my warehouse again, but the city is still under the warehouse, and claimed by me. The third problem isn't mine, the city is unclaimed.