Speed been steadily getting worse

[#1]

Hello
I had  fibre put in about 3 months ago and since it was installed it has been steadily getting worse and worse
https://imgur.com/QHhQZEs
I was told:-
https://imgur.com/UGVr2nQ
I am supposed to be getting 9mb,
I am getting 6, thats 33% less than what I am supposed to be getting.
The router is not unplugged regally but I have had the kitchen replaced so the power was turned off a few times over the last two weeks. Can I please have my line looking at? Maybe a profile reset?
Thanks.

[#2]

Hi,
I've tested your line and can see no obvious problems, the connection remains stable and your line speed is around 6.4Mbps.  Wholesale have adjusted the estimates for your circuit for the speeds to be between 4.4Mbps and 8Mbps (as can be seen here), so we may struggle to have a fault investigated.  However, I would be happy to arrange for an engineer to visit your premises to see if any improvements can be made to increase your speeds.  If you'd like an engineer visit, let me know and I'll get it arranged for you.

[#3]

Quote from: AndyT

Hi, I've tested your line and can see no obvious problems, the connection remains stable and your line speed is around 6.4Mbps.  Wholesale have adjusted the estimates for your circuit for the speeds to be between 4.4Mbps and 8Mbps (as can be seen here), so we may struggle to have a fault investigated.  However, I would be happy to arrange for an engineer to visit your premises to see if any improvements can be made to increase your speeds.  If you'd like an engineer visit, let me know and I'll get it arranged for you.

I feel pretty cheated BT have lowered the estimated speed.  What is the reasoning behind that? Is there a technical reason?
I know it's not your fault, I am pretty curious.