Terrible customer service

Besides the absolutely terrible customer service and continuous harassing phone calls, Today I get a call from an agent, after I say I am at work and put down I get 2 more phone calls. After answering the last one I am told “why are you putting down” and repeatedly being shouted at on the phone “pay your account , pay your account” this is totally unacceptable. I have sent an email which I am sure will fall amongst deaf ears. This company harasses me continuously even after stating I do not want to be contacted and will not pay through them.