why are aussie credits cards being rejected?

tried with several different visa/mastercards and none are working. clients very annoyed at not being able to pay for premium use. please resolve 

If the credit cards are being rejected, perhaps it means that the card is expired or there are no funds on the card. 

Alternatively, you can also try other Payment Gateway supported by JotFOrm like PayPal, PayPal Express, PayPal Pro, Stripe, Authorize.Net, Dwolla, Square, etc.

Mastering Payment Form Integrations with JotForm

However, if you mean something else or further assistance, please do get back to us.
Regards.

Hi Christian 

As mentioned, I have used several cards. All of which definitely have funds on them. I am in a real bind here as my clients are really suffering without theses forms being active!

If I understand you correctly, you would like to upgrade to Premium Plan? Please allow me to inform you that Premium Plan is not available anymore. The available JotForm Paid Plans are Bronze, Silver and Gold Plan. Please see our Pricing Page to know more about each Paid Plans.

Here's a guide on How to Upgrade My Account

Let us know if you need further assistance.
Regards.