Hi Amrit Koirala,
Sorry to hear about your difficulties. Based on the information you provided, I would advice you to open a case with the Learning@Cisco Centralizied Support team and I am sure they will be able to better assist you with your Cisco Id mismatch, so you can use your voucher.
You can get more information and open your case with the Learning@Cisco Centralizied Support team from the following link:
I wish you all the best in your CCNA exam.