Thanks for letting us know, could you send some videos? This would make it easier for staff to believe you.
Without video evidence we cant know if this is a troll or if its honestly correct the best thing to do Is direct message a staff member in game or on a discord forums etc with what's going on to direct you to the place to resolve the issue.
If you have video evidence of them hacking, make tickets here- http://grandtheftmc.net/support -either post the videos on YouTube or through file sharing on the forms. If you didn't record them, then we can try and take a look for them, but we cannot guarantee that they are hacking, and if they are, be able to catch them.
sorry i don't now how to film but another premium have filmed 1 his name is dragonzzzYT i am going seek a link