Woocommerce Subscriptions Payment Gateway Integration

Hi everyone,
to make SEPA-payment gateway work for us we need you to integrate this in our shop.
https://docs.woocommerce.com/document/subscriptions/develop/payment-gateway-integration/

we use woocommerce subscriptions in combination with a SEPA Payment gateway that comes from a plugin "germanized". Testing the gateway, the renewal fails - the documentation tells that the gateway must support modifications to the renewal date, like mentioned in the documentation