Volt 1 gen 2015,
When the car finishes changing
That behavior is very strange. The Vehicle controls the transition from State B (Connected) to State C (Charging) by pulling the voltage down from 9V to 6V.
What can be done to prevent this from happening?
We would recommend checking to see if GM has any sort of update for the Vehicle, or checking the GM Volt forums to see if anyone has had a similar experience.
The Charging station will not change from Ready to Charging without being commanded from the vehicle.
Here is something similar reported on Juicebox and Chargepoint very similar to your report.