Per the agreement you entered into when you signed up for Windows Mobile service from U.S. Cellular,

"Smartphone features may not be used for other purposes (e.g., continuous file transfers, telemetry, web camera posts, peer-to-peer file sharing) or to substitute for private line, frame relay or other dedicated connection. Such use or use of more than 5GB per line per month may result in termination of service without notice."

So, you have ABUSED your UNLIMITED PLAN. Seeing how you are in Chicago I think you'll be hard pressed to find any carrier with comparable coverage.

Best of luck to you!