Fibre unlimted speed drop since phone line was switched.

[#1]

As the title says, I have noticed a speed drop. When my fibre was first installed I was consistently receiving around 75-78mbps since my house is less than 25 meters from the fibre cab. This has since dropped and fluctuates between 50-65mbps. I remember my previous ISP telling me that they would "turn up the gain on the line" to increase my speed which seemed to work. Could my drop in speed relate to the phone line settings being reset which my phone line was switched over to PlusNet?
My IP Profile is currently set to 77.44mbps from the btwholesale speed test site.
Any info from the tech guys would be welcome.

[#2]

DO NOT get the gain turned up on your line - it used to help with dial-up connections, but has an adverse effect on DSL lines.
In any case, if you are only 25 meters from the fibre cab, there should be absolutely no loss, unless the cab is getting full and you are being affected by cross-talk.

[#3]

Fibre only became available on the 10th Jan in my area. The openreach engineer said I was the first in my area to have it. Why would my connection drop so much?

[#4]

Dunno. Best to raise a fault.