This is a message that I received from a support tech at Microsoft after getting a complex issue quickly solved. These folks are very responsive. When initiated through the 365 admin portal, the support response is rarely more than 20 minutes, either by phone call, or email. My choice.

Thank you for all your time and patience on this case. You were one of the best administrators I have ever ever worked with. You provided me with screenshots and gave me a lot of insight to guide me in the right direction for troubleshooting. I deeply appreciate and thank you for that!

Mitchell – Microsoft Corp.