Upgrade without consent

These people upgrade my plan without my consent. When I request them to downgrade they make excuses of their system giving an error of which they are unable to, i dont even want to start with their self service app, its absolute BS. Every month I get billed more than what I need to pay of which a couple the agents I spoke to confirm there's a credit on my profile, when I call in no resolution whatsoever. Every time "the matter is being escalated". I asked what the TAT is no one can give a valid answer.