(1.)Use IE,that will save you a lot of headaches and heartaches,and the older version you have the better.
(2.)If it refuses to accept the password you have always been using just request for a new one(again,I dont know why that only happens in FF and Chrome)
(3.)Since they know how "user friendly" their website is,they have user guides like
THIS to help you.
(4.)Be patient,very patient;mvumilivu hula mbivu.I finally managed to submit in the afternoon after almost giving up.