Stupid bell push problem

Here's a daft problem but one that HOL peeps might be able to help with. For the second time in as  many months our bell push has been pulled off the door frame and taken away. We share a front door as is the norm on Langham road. Our next door neighbours are fine and our shared hall neighbour has a big metal case type mains wired(not cheap) Our one was just the wireless type which you plug into a socket in the house. It is clearly the same person who did it before and we looked around for it. These bell pushes are unique to the unit so you cant just get the bell push. We assume its a slightly strange person who we maybe told to sod off for rummaging in the bin but we just haven't a clue. Do we have to shell out for a heavy duty one? I get quite a lot of packages and tho Ive put a sign up to knock on the window, its means staying downstairs all the time!