Steps#1 To create an office 365 Server request follow this
Note: D24/7 Support will be vary with the plan which you have
Step#2 Depends on what kind of support you need or issue you have you can create a ticket selecting your subject
Step #3 You have to select whatever support feature and Symptom
Step#4 It will require more details to add
Give your proper working number to continue the ticket
Step#5 Once you submit you can see status (Check my screen shot that will be pending)
Thank you and hope you help this :)