I've tried several times to upgrade from Basic to Pro using a valid credit card but each time I received the response 'We are experiencing technical difficulties' without any additional information.
By the way, there is a bug in this message function too--I clicked 'Submit a bug report' and the window that opened was 'Suggest an idea'.
You may contact me at uritadmor@yahoo.com .
Thank you,
Uri Tadmor