How Do I Unblock My Outlook?

My Outlook acct has been blocked for SENDING emails.  I can access my account just fine and can read my emails.  When I try to send emails, it pops up a message that "due to unusual activity" on my account, I am blocked from sending and need to get a code via my cell phone and reset my password.  I reset my PW 2 times and still am blocked.  I contacted tech support and have heard back from them that "nothing is wrong on their end" and I need to reset my password.  I have reset it 2 more times and am still blocked.  Supposedly it can become blocked due to sending out spam, sending out emails to large groups of contacts, forwarding spam emails, etc.  I have done none of these things.  I responded back to tech support that the issue still isn't fixed, but haven't heard back.  Their response time is 24 hours.  They did tell me that there is no phone customer service or other help available.  Has anyone else had such an issue and how did you resolve it?  Thanks!