Hi Sam,
Thank you for contacting the Microsoft Community.
I understand that you need to change the assigned name on the voucher, and I am aware of how important it is to have this accomplished. Allow me to provide further information to get this done.
Commonly, if the voucher code has not been utilized, the discount can still be reassigned by just providing the code to the new owner.
Meanwhile, should you encounter any issues in reassigning this voucher code, or the voucher cannot be reassigned already, you can coordinate with the person in charge of issuing the vouchers within your company or with the voucher provider directly to have this transferred to a different name.
Let me know how it turns out.
I look forward to your response. Please note that if no response is received after two business days, the case will be closed and locked. After the case is locked, we will no longer be able to respond, even through Private Messages. Thank you.
Regards,