mpx220 - EXTREMELY slow / non-functional internet

I've had my mpx220 for 2 weeks now (Cingular), and I've noticed that the internet connection was super slow 2 weeks ago and now doesn't even work. I can't even get to the sites in the favorites folder (media net, msn mobile, etc.) which are almost completely text-only sites, nor can I get to sites like google.com. My phone indicates that I have good signal and am on the GPRS network. I've tried the "WAP Network" and "The Internet" connection options, and set the phone to "Automatically detect settings" for the connection.

Right now I'm on the $7.99 Media Net plan for 1MB download per month. Could it be that I already used up my 1MB and it won't let me connect until the next month? I thought it would simply start charging me extra, and also I doubt that I even came close to using an entire 1MB. Can anyone help me with this? It's really ticking me off that I paid for Media Net access and the internet won't even work.