Very slow internet

I've posted on here before about very slow internet, but it fixes right away when I do post.

Now it's constant, I pay for 2gigs and I'm getting speeds like 2mb - 50mb. When usually before I would get 4-500mbs.

I'm thinking of replacing the coax cable to see if it works, since it gradually got worse. If that doesn't work then I'm not sure what to do. Maybe it's an area thing, I'm not sure at all.