The charge current on the OEM EVSE for 2011 is set on the EVSE not in the car. Selection is done by pressing a mechanical button on the EVSE which stays in the selected mode until it is pressed again to change the current setting.That would be the charging rate that you are using. If you have not set it to 12 Amps, then it defaults to 8 Amps.
I run mine automatically at 12 Amps in my "Home" location.
If the wires burnt up at 8 Amps, that is a serious problem. I would call GM (not the local dealer) and check on warranty.
I would think that they would be have liability if there was a fire. Much like the $0.50 ignition switch fix, they held off on, that killed many people.
VIN # B0985