FTTC - Speed halved

[#1]

I was regularly getting speeds between 27MB and 34MB down, especially after needing to turn the modem off and on after a disconnection.
Now it rarely gets above 10-15MB.
Am I doing something wrong or is this the speed its always going to be now?
Many thanks
Stuart

[#2]

I've done some testing but there is insufficient data to go one, as we cannot see a BT speedtest result.
Can you perform a test on the following page.
http://www.speedtester.bt.com/
To add, how many times a day are you rebooting the FTTC modem?

[#3]

I have completed the test.
The modem has had to be restarted about six times since installation last Monday but no more than once a day.
Let me know if you need me to do anything else.
Stuart

[#4]

Nope,
More than enough overall.
I have now raised a fault report. No appointment is required in this instance yet.

[#5]

Tried last night and got 26 down and 8 up.
Engineer came this morning, changed modem and faceplate, tested 34 down, 10 up.  He said if the problem did not go away they would have to change the port at the cabinet.
This is the test after the engineer left.

[#6]

I have now lost all download speeds:

After taking that reading I reset the modem but have not been able to obtain another speed test, it keeps asking for a license key.
Edit: Here is the reading after the modem was reset:

I had also updated the ticket with the result of the engineer visit.
Where do we go from here?
Stuart