Hi @Thomas Hickson ,
during the creation process in Azure Portal you will get a page with possible solutions based on your input before. On this page please click on Return to support request
. On the next page you should be able to fill in some more details and submit the support request.
Here an example:
(If the reply was helpful please don't forget to upvote and/or accept as answer, thank you)
Regards
Andreas Baumgarten