luke I'm gonna take a guess and assume you didn't fully complete the verification process before sending the money. As long as verification is not completed, account limits are comparably low in order to prevent misuse (you can read more details about this in bunq's terms of service).
When you complete the verification process you should be able to access the money. Go to [Profile] tab and click on your picture (the circle in the center) to see what step you are at right now. It might also be the case that you already started the verification but are still waiting on bunq to process it. That can take a few days.
