I was having troubles when I first signed up, as I couldnt log on with the CRN I had. So I called the website help desk and the guy was able to sort it out there and then for me, he created a new CRN and was very helpful..and I have been able to log on ever since with no problems.

Maybe you could try that.

I did my application online and the paperwork (sent to centerlink) at the same time so not sure if that makes a difference. I havent had to go into centerlink office at all.

Hope you sort it out soon, its so frustrating.