Worried about neighbors tapping in my Wireless

I have a Turbo Hub Netgear and my invoices for my download charge has increased $25 monthly. I do not download music or videos, I only play Facebook games. I have a neighbor across the road from me that made a comment one day she said: "You are the people that have the wireless hub" so I got thinking did she make that comment because she can tap in?

I would like to have some comments on this please.