The Self-Serve portal is always slow. Sometimes it's frustratingly slow. Once you click something on the page it's best to wait it out, it might hang (or appear to hang) for a long time but forcing it to re-load often seems to confuse whatever's happening on the servers. At worst, wait an hour and try again - often there's no problem or a problem fixes itself if you just give it the time it needs.
Clearing browser cache/cookies can help speed it up. Disabling scriptblocker and adblocker on the site seems to make it more reliable. It really doesn't get along very well with things like Ghostery.
On the plus side, if you (pre)pay your plan late there's never any charges when the account is suspended or when it's reactivated. You just don't get phone service for a short while. Your new 30-day (or 90-day) billing cycle starts on the day payment is received, you don't even have to pay for any days of suspended service (although you can miss out any Rewards on those days).
