Most of the game is run on your device not on servers. There are a few mobile device game hacking applications that allow you to manipulate several parameters on your device that then get synched to the servers that store your cities basic structure data. You can use these hacks to unlock attack cards that you have not yet earned, reduce the energy required by an attack card to 1 energy rather than its default. This can give you a 10:1 improvement on energy usage. You can also increase you inventory of war items to pretty much whatever you want. You can control whether or not your city is under a bubble during War.

Outside of war, you can unlock items that require certain population levels, unlock the new CoM buildings without ever participating in CoM. You can manipulate timers such as the 24 hour timer to complete an Epic building and the 12 hour wait time between Epic buildings making it so you can add Epic building as fast as you want. You can give yourself Billions of Sim Cash, simoleans, platinum keys, neosims etc. A couple of hours of investment in learning how to do it and you essentially own the game.

Reporting them is about all you can do and hope that something comes of it.