Qantas Cash website is currently experiencing tech issues (and was experiencing them last night) which can be seen at the top of the page:
We are experiencing technical difficulties and as a result, the Qantas Cash website is currently unavailable while we undertake emergency systems maintenance. We are working to restore normal service as quickly as possible and apologise for the inconvenience.
You can still use Qantas Cash for purchases and at ATMs at this time. If you need to contact us, please call 13 11 31 in Australia or + 61 (2) 9433 2329 if you’re outside Australia.
We appreciate your patience during this time.
When I registered last year I had no issues verifying details however this may have changed since.