You aren't SOL, you can stop using so much bandwidth. You can be a conscientious user of shared resources. Using a constant stream like that is almost always a bit lacking in legitimacy. It usually means you are using the service in ways that your service plan wasn't designed to be used, either you're downloading and/or sharing large, perhaps copyrighted videos, music, or software, or you are running a server for gaming or something like that.

Those 1.5Mbit DSL is "maximum capacity." Not what you should try to consume. Ultimately, all the customers go through one pipe, or a shared few pipes, so those hogging the lines negatively affect others.

In my opinion, it's the users of the bandwidth that are greedy. Do they really need 1,000 movies on their hard drives? Many bit torrenters have more content than they could ever watch in their entire lives...