INTERNET NOT AVAILABLE

I have a UPS and everytime with the load shedding I will use it but the problem with my ISP is that everytime when the ONT is plugged to a different source then there's no internet. The message I always get is Connected but no internet. This is really frustrating and have brought this to the attention of almost everyone. The last time Prudence called me I explained the problem to her and she was going to speak to her Supervisor and come back to me. I am still waiting. With or without a UPS am still without internet. I always call around to see if other people are experiencing the same problem but it seems they don't. What the use of paying for something I don't have?Net Nine Nine is a problem and their agents and technical dept is the same. I had many guys coming to my house but I am still not getting any joy. As I am writing this I am connected to my mobile data and that happens most of the time. With everything in their records they still will demand full subscription amount knowing that they don't provide service. I am tired of always complaining about the same thing everytime and the problem is I can't get another ISP as they have monopoly where I am staying. If anyone has an alternative please contact me. I need uninterrupted service but with Net Nine Nine I am not getting it. My hard earned cash is going into a waste. Their rehe****d answer after seeing the post on your Website is always "We are sorry" but they are not doing anything to better their service.