Basically the same thing happened to me!!
They forgot to enrol me in one of my units, which I'm not happy about at all, but luckily I'm a 2nd year student and knew what to do.
I emailed
enrolments@uws.edu.au and told them the mistake and they told me to just lodge a program variation form which I did yesterday, then I emailed them again to confirm that they recieved it and I am waiting for their reply.
I recommend you email them as you can put all your details in the email and they can look into it for you and let you know exactly what to do, other than that, yeah like everyone else is saying - ring the hotline