Intermittent connection issues and speed

I have had Comcast for a number of years and for the past 4-5 months have been facing constant connection issues, multiple times of the day. My connection gets dropped or speed goes down so drastically that internet practically becomes unusable. I have had technicians come and check my internet at 5 separate occasions. The technician changed the modem, filters, moved the modem from one location in the house to another saying he sees the connection better at the new location. My connection issues are not resolved though. When ever I call Comcast they ask me to reboot and check, but the issue is not continuous , it is intermittent and having a Comcast technician or rep at that very moment is not possible. I wanted to check if any one has such issues and troubleshooted them.