If the leader is gone, and they have not been around for as long as the SG auto-demotion is set to, then the next person in the group to log in should have been given leadership rank and permissions. This allows those who are still active to continue the SG and pay rent.
However, sometimes the rent issue gets screwed up, at which point a nice little petition to support should get you all cleared up.
Let me never fall into the vulgar mistake of dreaming that I am persecuted whenever I am contradicted.
~Ralph Waldo Emerson
"I was just the one with the most unsolicited sombrero." - Traegus
The problem could be that the base powered down and the current leader had logged in recently and didn't bother to pay rent. 45 days is a long time to wait for the auto demotion. So, yeah, petition would be a good step to take.
Or, before doing any petitioning, go into your SG settings and look at the "permissions" setting. You can set it so that only the leader pays rent, everyone can pay rent, or antyhing in between.
Find someone with the right rank and appropriate permissions and have them pay it.
If your Supergroup has gone defunct (or the leadership of that group). Is there any way to maintain the SG? How does one pay the rent if you were not the owner?