Is such ADSL-line diagnostics adequate by the operator's specialists (see details)?

Question

ADSL

The essence of the problem is this. There are two adsl lines. One works flawlessly, and the second will be discussed.
Absolutely identical modems hang on both lines, with a difference only in the registered logins and passwords.
And for the one that works flawlessly, the readings in the modem are as follows:
SRN Margin - Down: 30 dB; Up: 22dB
Line Attenuation: 20dB
But with the second trouble:
SRN Margin - Down: 4 dB; Up: 6dB
Line Attenuation: 37dB
(I rule out the modem problem, since I swapped them. And the modem from the "good" line showed the same disgusting line quality indicators)
And it behaves like this. ADSL connection establishes (sometimes breaks but reconnects).
If you open heavy pages with pictures and flash, then often the download just freezes.
If you simultaneously run endless pinging in the console, then in a calm state, pings run for 50-70 ms, without loss. You open a page on the Internet and pings jump up to 300-800 ms. Losses roll in.
They knocked knocking on the provider ..., they barely got through. They sent a person. He connected the phone to the line. Called somewhere to their operators. He made sure that there was a connection, something was heard there, notified us that everything was working, then he calmed down and went home with a sense of accomplishment. They say the line works, why are you soaring.
The line has remained shit.
Here I think. Is this the right job? What to do? Again bomb technical support and demand that a person come to check the performance of the line? So that this miracle engineer would come again and “by ear” (or whatever he uses there) determined both the attenuation indicators, and the noise level, and crosstalk, and listened to all 256 carriers ....
Will they send him again, so what? Write to the Ministry of Communications, Rospotrebnadzor? The operator is a monopolist and will not leave

Answer 1

Ask for measurements, report that there are no questions about voice communication, there are problems with receiving adsl, well, do not let the employee go until you explain the essence of the problem and show the results of the line test by modem

Answer 2

dial up works at voice frequencies (up to 3 kHz), adsl works at frequencies up to 1 MHz, you can try to change the splitter
, and line tests will help you - even if they say that the line is bad, what will you do?