I just got off the phone with customer service. I tried to add a ticket to our reservation but because of the childs age, I could not do it online! So I called your HORRIBLE customer service. As a result i lost the fare I was booking at. Your agent was rude disrespectful and not compassionate!! This is the third time during my flying with you that you have made my travel more difficult and more frustrating! I changed over from AA about a year ago and unless you FIX THIS RIGHT NOW, I will definitey be going back.
I am sorry about your experience; this is out of character for SW.
With that said, you should be able to add a minor's ticket to your existing ticket purchase online. You will purchase a new ticket for the minor, and toward the end of the process, a screen will pop up asking if the minor is travelling unaccompanied or with an adult. When you choose with an adult, the system will prompt you to add the adult's name and the confirmation # for your already-booked tickets.
Hope that helps!
-A List Preferred, Companion Pass holder, Community Champion.
When you say you "lost the fare" I'm guessing you were actually quoted the Child Fare which is basically just a slightly discounted Anytime fare and is most certainly more expensive than a Wanna Get Away fare that you could purchase for any passenger, regardless of age. As @elijahbrantley said you can purchase a Wanna Get Away fare for a minor online if you provide information about the accompanying adult's reservation. It's unfortunate this wasn't explained to you, but if you asked for a child's fare that's probably what you were quoted.
I am so sorry to hear about your bad experience with the customer service. I have the number at 1 (800) 435-9792 and see if you can talk to someone about problem that you had. For some apparently reasons, the agents may not have time to deal with the customers and you also can call 1-855-234-4654 and see if they can resolve the issues. Hope this will helps.