My ZA ISS V 9.3.014 is due to expire in 20 days, but every time i attempt to renew i get this message " Error Occurred - Correct displayed errors and try again please" - but there are no errors displayed.

To get this i have done the following.
Opened ZA, clicked on "product info" and click on "renew' which then opens this web page -
I then select the option i require (but happens with all options) and click "add to cart" a pop up displays about up grading to ZA Ex. Regardless if you click yes or no the above web page is re-shown with the above message across it in red. I have attempt several times over the past week but always with the same result. can one renew a different way. Thanks for your assistance