Changing domains

When I changed the extension of my domain it broke the sending key. When I tried to edit the plan it wouldn’t let me change the domain pointed to. Tried to cancel it so I can make a new plan for the new domain because there’s no option to save in the edit screen. So I cancelled it and its still there for a MONTH! Am I supposed to wait a month to use your service? I’ll just switch to MailChimp I guess.