The limit is entirely on the ISPs side so there is no way to increase the bandwidth from your end. As a crude analogy, think of it in terms of being a pipe. Even if you have a 5 inch pipe on your end, if the ISP only has a 1 inch pipe that's the limit. To increase the speed they would need to put in a larger pipe. (I told you it was crude)

I'm quite surprised that this sort of thing isn't more widely known. All devices use the same basic protocol structure so if it gets connected to the internet or accepts wireless signals, someone can get into it. The only way to completely secure a device is to leave it offline, then you need physical access to it.