I have SBC Yahoo DSL Pro...and I can tell you by experience that dealing with the "techs" can be a runaround. Can you post the results from a TestMy speed test please? Also goto 192.168.0.1 (your modem) and tell us what it says for connected at.
Example of mine:
Connected at 3008 Kbps (downstream)
512 Kbps (upstream)