Had this problem recently also, and visited this thread in my pursuit of a solution.
I was able to call my local service center and navigate through the service option to reach someone in a remote call center about charging. After I explained the issue, they told me they are looking into it, and removed the alert for the time being.
I was plugged into a supercharger while on hold, and was pleased to hear a loud connection sound as the supercharger engaged. When I looked up, the alert was gone.
So that was my fix. I'm charging while writing this.
A little backstory on what may have caused the issue in my case, for the curious:
I recently purchased the car, a 2014 Tesla Model S, from a dealer nearby. I am the second owner of the car, and the original owners had purchased (or received) free supercharging for (with) the car. Upon transfer of ownership, I received the upgrade, and had created an account to operate the Tesla.
Every time I took my car to a supercharger, I could plug it in, and it would charge. The "Current Session" section on the car's charging menu has never registered a single session. The mobile app similarly does not have a record of any sessions. So this is a potentially unique circumstance.
Additionally, the first instance of the warning popped up a few days ago when I supercharged and returned a few minutes past the grace period for idle Tesla's at Superchargers (or so I assume). So my theory is: The combination of the transfer of title and the connected account somehow interfered with the internal payment structure on Tesla's end, which was triggered by idle stall fees, and then prevented the vehicle from allowing supercharging as a result.
Or Tesla's amazing technology is still just a manifestation of our imperfect selves! It's been a great ride these past three months, and I'm excited to push the limits of this car many years into the future. I've already saved an average of more than $400 a month on gas and engine maintenance as compared to my last vehicle.
Thanks Tesla Team