Hi ​@As his , thanks for flagging this! That does look odd, do you see any error or notification when trying to assign the seat?
To cover the basics, please make sure you’re following the steps in this guide to assign a full seat: Change seat type.

If the issue persists, it may be due to a seat allocation mismatch on your account that needs a closer review. Since we can’t access billing details here on the Forum, the best next step is to contact our Support team so they can review your billing setup and resolve the extra seat charge.

You can submit a ticket here using your Figma email: Figma Support Form.
In the form, please also include a short description of what’s happening and a screenshot of the issue, that’ll help them investigate faster. Thank you!

No errors. I did send an email with screenshots. Let’s see.

Hey As his, good news! I see in the backend that the support team was able to solve the issue by adjusting your charge. Please check your inbox when you have a moment and feel free to reply to the case directly if you have any further questions.

For others who encounter similar issue, to prevent additional charges in the future, we recommend using seat approval settings to automatically manage new seat requests. This setting will require Admin approval for a user to be upgraded to a paid seat. Our Help Center article provides step-by-step instructions on how to change the setting.
I’ve gone ahead and close the topic here, thank you!