You can easily Stop detect Wireless Bandwidth Theft using simple tricks and methods , All you need is to follow below steps properly.

How to Detect Wireless Bandwidth Theft

Log in to you network router by typing the IP address into the address bar of your web browser. The IP address often is written on the router, but more often than not the address is http://192.168.0.1 or http://192.168.1.1.
Open the list of attached devices. This could be called “Status,” “Device List” or “Wireless Nodes,” depending on your router. You are looking is a list of MAC addresses or “clients” that are using your network.
Verify each device listed as your own device. If there are more addresses than your devices, your bandwidth is being used by another device.

How to Stop Wifi Bandwidth Theft

To Stop Wifi Bandwidth Theft use Scary Wireless Names like c:virus.exe or something like that which discourage user to use your Open Wifi Network.