You should try to gather more information first.

In particular, your DSL modem can probably tell you more about the signal quality on your line, from its internal web server, or with something like the dmt software tool (windows/unix).

For our line here, I have my 24/7 Linux server log the line status hourly, and after any connection reset:

Modem: Up, speed 2496/640kb/s, interleaved, atten 61.0/31.5 dB, margin 7.0/11.0 dB, power 19.0/11.5 dBm, resets=5

That kind of information can be quite valuable to have in hand before calling the telephone company.

In this case, you can see the S/N margin is quite low on my line -- 7.0dB downstream, and a better 11dB upstream. The "worst" usable value there would be 6dB, and ideally it should be 12dB or better.

Since the S/N is poor, the carrier wanted to downgrade the line profile to 1700/500, which would double the S/N, at the expense of low bandwidth for me.

So instead, I insisted that they use an interleaved (instead of "fast") profile, which spreads out the ECC data much more widely. This increases line latency by quite a bit, but makes things much more immune to line noise and retains the higher throughput.

Cheers