I'm sorry to hear about your issues with the 12V battery. Frankly, I cannot imagine having any car towed for a 12V battery issue. Even if someone else is footing the bill, towing often results in some sort of damage to the car.
Just one note about this: When I want to charge the 12V battery in our MY2011 LEAF, I DO NOT plug in the EVSE to the car. Why? Because when it is charging, the LEAF's electronics draw more current than the trickle charger can deliver. The result is that the CAR, not the trickle charger, controls the charging voltage. Unfortunately, the car doesn't always do a good job keeping the 12V battery charged. (Based on your post, this is apparently true even in the MY2015 in spite of assurances to the contrary by other members of this forum.)country5369 wrote:I went to leave and the car had a dead battery symbol and no response other than dash lights came on Tuesday night January 16th 2018. I plugged the chargers in and the next morning had green symbols on the chargers but still a dead auxiliary battery symbol. It was the all day with the temperature in a single digit. The car has now been on showing full charge status from the chargers for 48 hrs and the ambient temperature of the cab finally rose to 32* on thursday January 18th in full sun about 11 am when the battery symbol went off and the Leaf operated as it should.
Unfortunately, your 12V battery may be badly sulfated at this point. My experience is that my desulfating charger takes a long time to break up lead sulfate, but it really doesn't do much in cold weather. IOW, it seems to be much more successful desulfating in warm weather.
Good luck getting your issue resolved quickly and cheaply.