speed droped 4 times in a week - please have a look on my line!

[#1]

I am sitting at 39mbit/s download now - it was 59mbit/s week ago!!! what is going on on my line??? I got no response on support chat, no response on community pages! is this really what you call "great service" ? the snr value went up form 3db to 11db since last week!!! there is definatelly something wrong on my line. please see attached screen from my router.

[#2]

I can see my colleague has responded here: https://community.plus.net/t5/Fibre-Broadband/Drop-in-speed-again-in-two-weeks/m-p/1421778#M57449