Try an email. I was able to have an email agent backdate my start date for a challenge and gave me PLT last week even though I didn't successfully sign up for a challenge before flying. So, someone there has the power. I wasn't expecting much, and frankly after received 1 email back, wrote back thanking them, asked a totally unrelated question and dropped the issue. The second agent responded by saying she just made me PLT.

So you never know. I'd be nice and professional and just try to speak with another agent. Sounds like a strong case.