Southwest Airlines complaint: lack of communication

I was speaking to a manager over the phone about changes to my flights. I tried to explain to the manager that I had three flights I need to change. The manager said I cannot change my flight it would be additional charge of $189. I told the manager that doesn’t make any sense, I have changed flights in the past and according to my ticket. I am able to change with no cost he started to talk over me in got upset and hung up the phone. I called back a lady name Stalla answered the phone. I tried to explain to her what happened and can I get assistance , I asked Stella can you look up all my flights under my name and make sure they’re correct she says no I’m not able to do that and hung up the phone. No one would assist me with my flights change or my issues when I called back again front Desk flight service name John answered the phone and I asked to speak to a manager he wouldn’t allow me to speak to a manager. He hung up the phone. My flight ation number: 4zu007