Website is terrible.
Card issues come from using a card ad-hoc then trying to buy longer-term access. You can;t use the same card. This is not mentioned on the site.
The “invalid” on the contact form is if you use ANY punctuation. Emailed them about this on more than one occasion, and have been ignored. Actually, I’ve emailed them on many occasions via the form and although I get an email “we’ll get back to you within 5 working days” I have never heard anything.