Guys, wanna ask for some advice.

I have a very low rating Local SNR Margin at NIGHT, I can't even connect properly. This only happened at night and the line connection works great at day.

At day, the Local SNR Margin can achieve to 25-30, at night, it only has <15. I have gave a call to 100 and the person told me that their technician doesn't provide internal wiring. They suggest me to find the construtor or any specialist to change the internal phone line. So where I can these specialist? Do I need to change the external phone line too?