Disappointed by Rain service

I am disgusted and appalled by the service I received from Rain. The network has been overbilling me for the past three months. They have been charging me for a 4G plan which I upgraded from and the new 5G plan which I took. I called today trying to sort out the matter, the agent (Kwanele) told me it’s my fault that it was not cancelled and it’s my bill to foot because it’s my account. I don’t understand how it’s my fault when the agent who helped me initially, didn’t cancel as agreed. I am utterly disappointed at this service