Very slow speed + Ping lag and connection drops

[#1]

Hi,
I’m having trouble with my broadband the speed was great at first then it started disconnecting we had a BT Engineer fix our ADSL Box which fixed the disconnect problem and the speed was fine for around 1-2 months.
The speed as dropped from 8 to 10MB to 4-2 MB in the last month, high ping spikes even if someone is watching a YouTube video.
I have tired resetting the router to default, unplugging all other devices connected to the router i.e. Wii, iPhone, Laptops.
Didn't fix the problem, I can barely download a MP3 file or watch a YouTube video without it disconnecting or crashing.
I don’t know what the problem is.
I have attached a picture of my router speed
Thanks Ethan

[#2]

Hi there,
I've Just been checking your account and couldn't see an obvious cause for the drop in speeds, however the SNR looks quite high for the speeds you've had previously so I'm going to push a reset through to see if that comes down to 9db and pushes the speeds back up.