Problem with renewing domain

Hi,
I’ve had an email from WordPress saying it’s time to renew my domain. When I click on the link to do so, it keeps asking me for my first name,even though that’s entered already. I’ve tried entering a different credit card, I’ve tried erasing my name and re-entering it, but the problem persists.

I don’t know whether it’s relevant, but within the past year, I’ve moved my blog over to WP.org from WP.com (or rather, I paid WordPress to do so because I have no IT skills whatsoever).

Any advice please?
Thanks, thetwistedyarn.com