I haven’t, but I left the EU a fair few years ago.
I think that you should use the contact form on this page:
https://www.isc2.org/Contact-Us#accordion-5d0a09572cfe44d5b0251d0fdfdac3a1
Member support should be able to help you.
As much as I have experienced in similar situations, it is simplest to pay personally to the service provider (for example to (ISC)2) at first. After that you can present the invoice to your employer who can use it to pay the same amount to you. VAT part can be problematic in same situations but usually it is not worth of extra bureaucracy.
Will ISC2 provide COR (certificate of residense)? I tried to reimburse my exam voucher payment, and my company also request COR document.