Endless disconnecting

I have had 4 appointments now. Each time they replace my coax and tell me i am good to go. I call comcast and they always make me a new case. It has been almost 2 months and i am starting to give up. When you call they tell you the internet is good. And reset the modem. This is a intermittent problem and i cant get them to fix this. After the 3rd appointment they said it was the line from the box. So they scheduled a drop line. I called comcast 2 weeks later they said it was done. It never got done...... So i had another guy come out. And guess what? He replaced my coax again. Im hoping someone from comcast sees this and helps me. I am hard wired in to a pc. And i have tryed 2 different computers just to rule that out. If i check my modem i have tons of t3 and sync errors. I tryed telling them over the phone and they say, no you dont we can see from here. Well i do. When i call they have no knowledge of my previous appointments. And i keep starting the same run around with no results. What should i do. I have no idea at this point. And when i say coax i mean the coax in my apartment. Its literally 6 feet long. Thats it. But if you look outside where it comes in, its stapled to the wall, has 180 degree kinks in it and looks like it has 10 coats of paint. And the box outside where it comes from sits in a foot of water and all the lines just sit in it and soak. Im sure at one point the coax was fine out there. But not anymore.