Hi,
If you used the resources in the Prod or Active account you will be charged, did the Lab open in your private Tenant instead of the Training Course? Kindly raise a billing case with the team via the portal - https://learn.microsoft.com/en-us/azure/azure-portal/supportability/how-to-create-azure-support-request#go-to-help--support-from-the-global-header
Hope this helps.
JS
==
Please accept as answer and do a Thumbs-up to upvote this response if you are satisfied with the community help. Your upvote will be beneficial for the community users facing similar issues.