The bloke in 2012 could have done the same thing, if he had an ounce of competence, as could the others.
What gripes me, is that I could have done it myself, but I'm not allowed to!
This sounds exactly like my story, except the story started in 2013 and the "ultimately in 2019" has not yet occurred here... still waiting.
One tech has actually said the lead-in cable needs to be replaced, but he did not have the authority to order it done.
I've had the same issue, but slightly better -- I was lucky to get the same tech twice, first on the service call when everything seemed OK, and then again when I'd done what he told me and it did not work. In Sweden, the
standard phone jack is of a construction that cascades the outlets, leaving one as the first outlet counting from the line. This is where DSL splitters must connect in order to preserve quality and connectivity. He'd told me to exchange the first jack for a quality one, and he also remade the punches in the Krone LSA-Plus I'd put in before that jack. This did not help, I found out, since the problems persisted. I registered another service request with Telia, and was lucky enough that I got the same tech. I was not able to be home for the service call, so I told him as he called me to set up an appointment, that if he switched to the orange/white pair in the lead-in instead of the blue/white I was more than happy to swap indoors as soon as I got home. I came home to find "no Internet" complaints, took out my LSA-Plus tool, and repunched the first line from being on the blue/white pair to the orange/white. Modem linked up, full speed, and never again failed. A couple years later, I was finally able to get a fiber connection, whose local-loop has worked flawlessly all the time.