Adding MailFrom addresses

Question

Hi

I want to change / add an MailFrom address, but the "Add" button is disabled. In the help it says I should contact support to raise the quota. I have been following the article about that, but it doesn't work for me since I can't open a support ticket there - it just says again I need to ask to raise the quota.

(The accepted answer here doesn't work because of that:
https://learn.microsoft.com/en-us/answers/questions/1659365/add-button-greyed-out-in-mailfrom-addresses
)

Can you please help me raise the quota / add en EmailFrom address to the Email Communication Services Domain?

thank you,
Boris