Slow speeds and closed tickets for 6 months

I have had several people come out to look at my internet and see why I drop to sometimes single digit numbers on 2gig speeds, It has been said from xfinity maintenance techs that its the box outside feeding the internet, some of the equipment is old in it and not updated causing frequency issues. I have had many tickets to get the box repaired and Ill see the maintenance truck pull up, person doesn't even get out of his truck. stays for about 20 seconds then drive away. I'm getting kind of tired of this. I keep calling and all I get is the "If you still have service its not a priority" excuse. Not getting even half of the speeds I'm paying for should be the priority. I would have switched ISP's a long time ago but sadly comcast is the only service provider I can get.