Apologies for the long back story...
I moved back to BT with some intrepidation a couple of years ago when fibre became available. I signed up to "option1" which was 40/10. Then we got a free upgrade to 56/10.
Next, we got a free upgrade to infinity 2 (80/20) speeds because line rental went up. Cabinet is close so I connected at 72/19. All was fine.
The contract had to be renewed recently, sales rep said we could stay on infinity 1 but would still get infinity 2 speeds due to previous upgrade.
Contract day came and surprise surprise we went back to infinity one speeds. Cutting out the numerous back and forth with sales and support the solution was we had to recontract to infinity 2 at a reduced price to get the speed back. When that kicked in we went to 53/20.
Lots more back and forth, it seemed a BT retail issue with how they set the package up.
A second openreach home visit saw us with a new card in the cab (same stunted speed) then after some wiring changes between the cab and our house we The engineer was alsended up with 70/20.
The engineer was also the local REIN guy and he identified a source of noise which he says had been causing the issue (he demonstrated this with a radio at 612 khz). which is why he altered the wiring, he said he had done something to move us away from the source. The noise source is still there, heard clearly on my car radio.
Now the question smile
How come the speed was not being affected by the REIN prior to BT retail recontracting us? Seems odd to me!
BTW, a great engineer, gave a bottle of wine when he came back the next day to collect the driver he left in the garden