Just to add a bit more, while speaking to the CS person on the phone I was told, "the FAs would NEVER place a child alone on the plane....unless the child is over 9, because at 9 a child is fine flying by themselves."
Isn't it interesting how the airlines decide when a child is old enough/mature enough to be alone? I get that kids fly as unaccompanied minors all the time (and the airlines set those age guidelines), but to basically imply that I was being unreasonable by wanting my child next to me (it was in the tone, impossible to convey in text).
I offered to pay for upgraded seats and was bluntly told no. They basically told me that there was nothing I could do and I would have to take my chances at the airport.
It was super stressful for me. I will say that I plan to do EVERYTHING in my power to avoid flying with this airline ever again. I can see why they are in bankruptcy and hope the courts make it very painful for them to ever recover.