Secure business/home internet been compromised.

I believe my neighbor and not sure who it is has been accessing my Internet and there are in my computers turn on my phone I need somebody knowledgeable about the developers and get hard and all that stuff where they can you know stop it and show me how to keep them off my Internet and in my business it's getting to the point where somethings going to happen I would really prefer her not to so if somebody is knowledgeable too I don't need a firewall Amin or any virus or change my password it's a lot more than that so if you're knowledgeable please call me as I need your help