How about Shenzhen Airlines? Is the service good?

Charging standards for child care on board the aircraft: Air China: Children aged 5 but under 12 years old and traveling alone but under 18 years old must apply for unaccompanied service; children aged 12 and under 18 who are deaf/unaccompanied Blind teenagers, deaf/blind teenagers who are over 16 years old and under 18 years old, can voluntarily apply for unaccompanied minor services. Free services are provided for children aged 5 to 12 years old. For those over 12 years old, the domestic direct flight service fee is 200 yuan and the international direct flight service fee is 260 yuan.

China Eastern Airlines: The regulations are similar to those of Air China, except that China Eastern Airlines requires children aged 5 (inclusive) to 12 (inclusive) to apply for unaccompanied service. There are no clear regulations for teenagers over 12 years old, and China Eastern Airlines does not need to charge service fees.

China Southern Airlines: Children over 5 years old and under 12 years old flying alone must apply for unaccompanied minor flight service. Children under 18 years old can apply voluntarily. Children aged 5-12 enjoy free service. For international flights, in addition to air tickets, a service fee of RMB 350 is charged per flight.