Submit Form on Sign Up bringing up 500 Error

On this page:
When a user fills out the form on the right and presses SUBMIT FORM it brings up a 500 error.

The logs on the server are saying this…

2020-01-16 14:19:10 AH01071: Got error 'PHP message: Connection refused\nPHP message: PHP Fatal error: Cannot declare class Stripe\\Stripe, because the name is already in use in /var/www/html/wp-content/plugins/s2member-pro/src/includes/classes/gateways/stripe/stripe-sdk/lib/Stripe.php on line 11\n'

The site uses S2 member and is hooked up to Stripe. But Stripe are saying they are not getting any logs or errors so the problem must lie with S2 Member somewhere.
All plugins and licences are up to date and I haven’t changed anything so I’m really stuck. It was working fine last week.

Can someone help at all?

Maybe you have an error in your form, please re-build it and tell me results.