Internet speed has been manually brought down

For a very long time our internet has been horrible and we have had a bad experience. We pay for 3-6 Mbps, but we don't get the speed we need. It goes as low at 0.08 Mbps and half of the time I cant even run a speed test. It takes minutes for me to look something up. When I reboot the router and run a speed test right after it hits the 6 Mbps range, but after about 2 minutes it goes below 1 Mbps. We called and they guaranteed us Uverse and the technician came out and tried but said that we couldn't. We then two different times have tried to upgrade our internet speed and was guaranteed higher speeds, but every time they tried our internet would totally cut out and not work. It seems as if our internet is being brought down on manually, because at times it can go up to 6 Mbps. We do not have fiber or Uverse because it wont work or its not available in our area. We have even had problems where the technician has unplugged us from the box and plugged someone else in almost like there is not enough space. Our internet has also been cut off because we did not switch to Uverse when the tech told us we can get it. Need help and right now i can play games or watch videos at all.