I e-mailed support again few days ago and got a reply stating my case has been assigned to a specialist team and I have been given a case ref.
They looked at my Zen speedtest results and admitted I have slow single thread speed issue and told me to carry on testing speed using the Zen speedtest.
I've told them the Zen speedtest is giving false and inaccurate results. The speed shown in Zen speedtest are higher than I'm actually achieving when downloading test files from websites, and running speedtests on Thinkbroadband.com to test my download speeds.
The speedtest on thinkbroadband.com seems to be more accurate at showing true download speeds. It has now started to affect HD streaming on Youtube and Netflix, videos keep buffering if in HD.
http://www.thinkbroadband.com/speedtest/button/14636...
They ran some tests and showed no issues.
KBD Test:-
Test Outcome Pass
Test Outcome Code GTC_FTTC_SERVICE_0003
Description No problem found, OAM test is not currently supported on this line.
Main Fault Location OK
Sync Status In Sync
Downstream Speed 79.9 Mbps
Upstream Speed 20.0 Mbps
I'm now just waiting if they will fix this issue soon, if ever.
Edited by knight01 (Thu 19-May-16 19:22:34)