This sounds so much like the issue I am experiencing...BT problem solving really is poor.
I've moved this to your own thread so you can seek a solution to your problem. Problems may seem the same but every line is individual and may have different causes.
Can you give some more details of the problem
can you post stats from your hub if hh6 then advanced settings then technical log information. If hh5 then troubleshooting then helpdesk
check for noise. Dual 17070 option 2 should be silent and best with corded phone
enter your phone number and post results remember delete number https://www.btwholesale.com/includes/adsl/main.html