Worst support ever

We have been struggling with an unstable internet connection for three weeks. They are unable to sort it out. They expect their customers to do their troubleshooting for them. Each time you speak to a different person. They fail to follow through to solve issues. I have tried to speak to a manager - they just take messages. Once they have signed you up you are left to struggle on your own when the wheels come off. I note they do not even bother to respond to complaints on different forums.