I threatened a chargeback once due to an unresolved billing issue. Went all the way to the VP of my Group for my state. Upon speaking with him they resolved the issue enough so I didn't pursue the chargeback. He also advised me when they receive chargebacks they consider it a non-payment of the rental and you are put on the DNR list. Imo that's a huge price to pay for not receiving your promised Executive Selection service.
Also what would you do if you got there and the EA/ES aisles were completely empty? Do a chargeback if they gave you a vehicle from a different row, or in your reserved class? This happened to me before. Got to MSP at 5:00 AM and all they had on the aisle was minivans or a beat up Nissan Versa at the end of the Alamo aisle. They told me take my pick as the car porters don't come in until just before 7:00 AM. My reserved class was full size. I left in the Versa and just came back and exchanged for a Maxima later in the day.
My suggestion is you'd most likely be better off to send a complaint to the social media department at National or to the Emerald Club. Ask for a free day posted to your Emerald account for the inconvenience. Most likely they'll give it to you to appease you.