Problems with the network and with the wifi/modem

Good morning, all this new adventure is started the 3rd May 2016.
The first days everything was working well and the speed test was fine according to the bandwidth for which i'm paying.
But suddenly something has begun to goes wrong.
The speed is often unstable, right now i can't show my daughter a cartoon in NETFLIX. Different times happens that the router simply stop working and most of the times the restart is enough, but sometimes we need to wait the line come back, for example one or two weekends ago the line was off for almost three or four hours.

All this it is happened in not more than three weeks, is it possible talk with someone to solve this issues?

regards