Which hub do you have?
have you tried a different browser to see if you can run the diagnostic test as that is the only test that will show your ip profile which controls your download speed
domyou have an NTE5 master or is still old style?
try quiet. Line test. DiL 17070 option 2. Should be quiet and best with corded phone
As IMJ has said, you need to check your IP profile, as that is what is restricting your throughput, as you connection speed if fine.
if they were changing your profile and that was an email last friday then I would have expected it would have been done by now
can you run btspeedtester and post the results must be done with wired connection
If you are still using the test socket and getting buzz on quiet line test then you need to report a phone fault to 151. Until you get a good quiet line I can't see your broadband improving