intermittent connection issues

I do not even know when it began, but I do know that it has been 4+ months. My connection drops varies, sometimes it will drop every 20-30 seconds for an hour, sometimes it will be good for an hour, it is just very frustrating. I have had 2 technicians out the first one stripped the ends of the coax cable and replaced the splitter coming from the box outside, and the second replaced the wire coming in from the telephone pole and the coax cable coming from the box outside. I also got a new modem that they sent me to "fix" my problems because they said my other one was "out of date" but ended up sending me an older modem then my last. I really need help