File a formal complaint

How do I file a complaint? I have been on the phone for 4 hours and have been transferred to 7-8 people. I’ve been told someone is changing my plan and then the next person has no idea what I’m talking about.

This has been a complete waste of time and my issue still isn’t resolve. I have work to do and I still don’t have internet. The worst customer service experience I have ever encountered.

Please help me resolve this