1. That connector may be outdated or a marine plug, and hard to find a mate. You might think of replacing with a male 30 amp connector that you could find many 30 amp cords to connect to pedestal. Be sure your electrical service is 30 amps.
Check for a switch near the entrance that might be a battery disconnect switch. The fact that 12 v works on charger but not batteries could be a bad solenoid or fuse between house batteries and 12 v fuse panel.
You may wish to read this for more info on typical RV electrical systems:
The 12volt Side of Life (Part 1)