I just went through the same thing with Comcast. Called the night it started and the Tech on line saw that I had a Node gone bad and that they were working it. He told me that 60 of 69 people on the node had already called in. There was no other info beyond that. No estimated time of repair or even what was wrong other than node issues.
I call the next day and they told me there was no problem and it was on my end. They continued to tell me that my signal way good. You could not get them to understand that it was a connectivity issue and that they were having partial node issues. I kept loosing sync every 3-5 minutes.
Called again the next day and after the fox went around the rabbit hole several times I asked for a manager. Instead I got a Sr Tech and he again insisted that it was on my end. I explained that I'm a Work Group Manager and I had brought my tools home and from the box to my house was perfect. I caved and told him to send a tech then. The Tech said I had the best line and signal he has ever seen and could not see any problems. Then I showed him my logs from broadbandreports line monitoring I had been doing. 32% availability for 7 days then it went to 56% then to 72% and dropped to 21%. Then he followed me to the front of my neighborhood and I showed him the node. I wounder why the node cover was gone and the ground was freshly dug up. He called in and after 10 min he said that I did have a partial node connectivity issue and they had no idea how long it would take to fix.
I e-mailed my spreedsheets and got three months credit due to the trouble and no one knowing anything. Don't let them talk you in a circle. Monitor it yourself, log and track it and send them the proof. I guess they fixed it tonight, my speeds are back up and running. Good Luck