Congratulations, at&t !
You've won the award for 'most useless customer website' for the 5th year in a row!
With an average functional up-time of less than 50% (this user has had, over the last 3 or 4 years, an average of about 3 successes in paying his bill out of every 10 attempts), your dedication to making your website either inaccessible (users can't even log in due to bad web programming), annoying (new "site keys" required for each visit), cryptic ("Not available at this time, Code 02431"), and with incomprehensible "business hours" ("Please try to pay your bill after 6 PM on Sunday") is OUTSTANDING amongst the millions of poorly implemented 'customer bill-pay' websites in the U.S. and abroad.
Figure: the latest failed attempt to pay my phone bill, February 24 2008.
Your webteam should proudly display the award (a bronzed pile of poo) at your corporate headquarters. Look for it in the mail.