Finally, after five years and countless calls, this is resolved and the upgrade was done. Sonic was wrong time and time again. The information that I had given them was correct in the first place. I was always within the proper distance. Two pairs going into my home were flagged and couldn't be provisioned due to line quality, but that was a repair issue. AT&T wouldn't take a repair request from me, since Sonic was their customer. Sonic wouldn't put in a repair request, even though they were entitled to, because AT&T had the pairs flagged as bad. I wasn't allowed to ask AT&T to unflag the pairs, but it finally got done, not by Sonic.
So I scheduled an upgrade in February, and here we are only seven premise visits and five months later, and the upgrade is done. Of course, it could have been done faster. I knew that the lines were bad and couldn't be provisioned. I told that to the AT&T tech, who didn't need to be there in the first place, so he thanked me, confirmed things, and called for the repair. The third person showed up after that, decided that my primary pair didn't measure as clean, and called in the fourth person. Then nothing. Somehow, the upgrade got canceled. Sonic doesn't know why, but they called AT&T to come out, and AT&T thought that they were there to do a repair. Since there was no open ticket for the upgrade, they had to leave. When they came back, they wanted to look at the jack in my home, which they couldn't get to, so they left. Finally, somebody came out, I explained that the jack was fine, and there was a note from a prior tech at the demarc point showing which pair to use.
Sonic could have called AT&T five years ago, said that the other pairs didn't measure cleanly, and they were entitled to the repair. Then an upgrade would have been simple with one visit. Even this time around, when they agreed that I was entitled to an upgrade, they could have told AT&T what I told AT&T, and they could have had the lines fixed first and then dispatched somebody for an upgrade.
In the meantime, Sonic has a record somewhere of all the support calls, and all the wrong information I was given, as well as nonsensical explanations.
So for anybody else in this situation, the best solution is probably to change ISPs.