Welcome to the foum.
This is a developer forum run by volunteers. For OpenAI support you can go here: (https://help.openai.com) (https://help.openai.com/en/articles/6614161-how-can-i-contact-support)
Also more information can be found (https://help.openai.com/) specifically (https://help.openai.com/en/articles/8264778-what-is-prepaid-billing):
“4. Expiry and Refunds: Purchased credits expire after 1 year and are non-refundable.”
There are a number of threads where people have asked this question though, you can search top right, here is another example: (Seeing today that prepaid credits will expire.......WHY..?!)