I have currently moved into a new place that is on BT and am experiencing incredibly high and unstable ping (varies from 30ms to 500ms) that tends towards high. As well as this upload speed is virtually non-existant with uploading images (~500kb) often timing out or taking at least 30s. Download speed is poor too at about 8mbps (or 1MBs).
Here is a tracert to Google showing my connection to the router (using ethernet) as fine but massive lag between hops so maybe there is an issue on BTs end?
The only reason I can think it would be this poor is that I am on a connection with multiple people (semi-student accomodation) but even testing at low traffic (about 5am) gives similar results.
Here is a ping log:
I also noticed that downloading something on my PC causes my phones connection to become incredibly slow too.