What is the point of the speed estimate given at fibre sign up

[#1]

I signed up to fibre and was advised that the expected speed was 50Mb/s +/- 1Mb/s
The initial sync was 48Mb/s and after a problem with losing PPP connectivity for an unknown reason (almost a week with no internet although the modem remained in sync) it dropped to 44Mb/s with quite a large interleave depth also the upstream is 10.89Mb/s fast path
The BT page gives a clean range of 68.6 - 50.3 down and 20 - 14.1 up
The latest note on my fault ticket states

Quote

The circuit that you are connected on can achieve speeds between 40Mbps to 50.9Mbps. Anything in between this our supplier would not class this as a speed issue

[#2]

To be honest, I have no idea how Plusnet get the expected speed anyway. OR quote a range...

[#3]

They use the bottom of the clean range - see pic on my post

[#4]

Also you will tend to find that speeds must be 20% or further away from the minimum (clean) estimate before it can be treat as a fault. Sometimes if the line has performed well for a long time and suddenly dropped, an argument can be made that the line is capable of more and then plusnet will be able to justify a fault being raised to Openreach.

[#5]

What Modem and Cab do you have Jim?

[#6]

Huawei Cab and I am using the Billion 8800NL which gave a slightly higher speed than the Huawei modem
Note I started off with an ECI modem but after losing internet for a week (getting the BT Wholesale page) which sorted itself out for no apparent reason a day before the BT engineer came I had it changed by the BT engineer to a Huawei one when he came
The attainable speed is shown as 52Mb/s which I assume is what I would get on fast path
To address the reason - I think is behind the question - the G.IMP is version 2 downstream only

[#7]

That was the thought at the back of my mind.

[#8]

When I signed up for fibre I was quoted 20Mbps, when I signed up for PNTV I was quoted 14 Freeview channels. If I have believed either I wouldn't have taken either offering. They were both b*****ks. I understand my line and locality better than an agent reading his script and the data on his screen.
I get a steady 28Mbps and 150+ channels  
It's not a job I would like, and I always show respect and am as pleasant as possible, just let them go through their lines.
But why oh why do ISPs raise expectations with "up to" speeds. And then Which magazine has waided in with a totally inappropriate campaign  

[#9]

update
just installed dslstats and it reports that G.INP is not enabled

[#10]

Quote from: PeterLoftus

But why oh why do ISPs raise expectations with "up to" speeds. And then Which magazine has waided in with a totally inappropriate campaign

Hi Peter,
At the risk of going off topic... that is because that's the Ofcom rules and Which? frankly do not know what they are talking about any more ... which reminds me, I really ought to cancel my subscription!
Which? were a worthwhile organisation many years ago, but they lost credibility with me many years ago when they sought to compare Apple Macs with PCs back in the days of Windows 3, but chose to pitch the product comparison of a PC running DOS compared to Mac running whatever Windows like OS it had at the time.  Clearly an unbalanced and ill informed review.  The response I got back showed the same lack of insight.  Since then I have seen very little good come out of Which? - the recent campaign shows that they have clearly lost the plot.
Kevin