You're getting grossly overcharged. With lots of time and patience, you can get to something more reasonable. The 611 people have no clue about data or blackberrys.
Bad news: you still have to call Cingular. Good news: you should call the data people instead of 611.
Look at Success with Cingular, TCP/IP, and wap.cingular
for my tale of woe. You may have to try several times to find a person on the other end who understands exactly what you want to do, which is no doubt very different from what I wanted to do. The cingular people are not well trained about phones, much less BBs. The data people are somewhat better, but you'll still get a confused one over half the time.