The subject is the message!
The customer service drawbridge is up and the gate locked. Every effort to make contact and raise a complaint/get tech help/fix a situation (very erratic broadband and dropping uploads) is rebuffed by circular links which go nowhere.
What is wrong with either the Help and Support or the Complaints pages?
If you need to call then just use 0330 123 4150.
Perhaps if you start a post stating what your problem is, forum users may be able to assist you in resolving the problem.
Here's a direct link to the broadband test but you will have to log in to MyBT & almost certainly have a BT Hub conncted:
https://www.bt.com/help/broadband/fix-a-problem/broadband-and-wi-fi