Non working internet

Very month near the end internet is almost non exsisting, and when we reported it we wore told we downloaded so much even well its uncapped the line will get slow. So we were lenient and tolerated the slow line. Then 1 month we were hardly home we didn't download only browse here and there and again the line was slow. So that we couldn't understand and we reported it and they said they will look into it. We haven't heard back its the beginning of the month and are internet isn't working. It this is how your service is then and half the time are line doesn't work then I suppose it's only fine I pay half of my bill since I'm not getting what I pay for. How many time must a person report problems before something is done!