Packet loss getting worse since April

I've been struggling with daytime packet loss here in Houston since early April. At this point my average packet loss is as much as 60% anytime between 7:30 a.m. and as late as 11 p.m. It affects anything I'm trying to ping beyond my /29's gateway IP. From the next hop onward, packets drop left and right.

Overnight, things seem pretty good. But during the day, I can't maintain a connection to anything. Phone calls drop, my office VPN disconnects, web sites stop responding… it's useless.

I keep calling in about the trouble. Over the course of all this, everything has been replaced: the cable to the tap on the pole, the grounding block, a splitter inside to attenuate the signal because it's a little too hot, all the connectors. On my side, I can leave a laptop plugged into the modem with nothing else connected, and the packet loss is just as evident. Nevertheless, I've gone as far as replacing my firewall. I don't know what else there is for me to do.

The last tech who visited was able to see what I was seeing, at least, and put in a call to plant maintenance. No word from plant maintenance though. Nobody seems to know what's going on or what to do next.

I've done a chat, seen two techs, and had at least one maintenance tech claim to have tried to reach me, but of course I have no record of a phone call. I do get calls from Comcast asking if they can close the ticket because it appears to have been left open accidentally. I explain that it is no accident.

What could be causing a problem like this? Is it likely to get resolved, or is this the sort of thing that just never gets fixed?

Past two daysPast weekPast 3 months, showing how this has been steadily worsening since April