can not go back to original plan

I am a customer for cricket for a long time. Last week I add a hotspot for my plan since the 'shelter at place' on the condition that the agent told me that I can go back to my original plan. I conformed with him several times. Now after a week, I removed it and the agent said I can't since the original promotion is not available. The first 2 agents listen to my explain and said can get my original plan  to me but unfortunately the phone get disconnect in the middle. After that no matter how I explain that when I made the changes and the agent said I can go back, they won't listen to me. I wonder how and where to complain this. Thanks