[FTTC] Install speed not as expected

[#1]

Thread here as per recommended on this thread: http://community.plus.net/forum/index.php/topic,106295.0.html
Well, fibre installed, and the max attainable speeds are a little pathetic. (Can be seen in reply 4 from the thread link given above). Ive telnetted into it, seen what there is to see. Cant work out why the max attainable speed is just 55meg, even though the cabinet & line length is about 60-100m away. Engineer thought I could get full whack 80meg trial speeds, but he didnt test with a sync machine thing (as apparentley it was broken). I think i can confirm the line is not aluminium too, as the line has been rock stable pretty much during its ADSL days, no major faults or sync speed drops.
So, 55 meg on a line 100m away from the cab? (Map also attached on reply 4 on the link given above). Something surely seems wrong? What to do now eh? 

[#2]

I am aware no one replied to this, but im just posting for reference, thats all.
So I raised a fault with Plusnet about it. Engineer came out, did some tests. Pretty much confirmed I was on the cab in question, so the distrobution side is VERY short. Tested here with a HAWK tester thingybob, got 48meg downstream, 19meg upstream. Said he would be back 2mins later. Comes back about an hour and a half later and says that the line was on a 60meg banded profile and he was getting full 60meg banded at the cabinet, suggesting a lot more headroom here. Came back to the house, requested the banding to be cut off the line, got 50meg this time. Was going to look at the manhole place it seems but the bloke said he didnt have authority to as the connection was over 35mb and left.
Oddly enough, he suggested that BT should test at "Ground Points", but he did not have the authority to do this, and niether did he know how to do it! Claimed that replacing the line underground would most likley fix the issue but as it was on 50mb, an engineer with higher authority from BT would need to come out and fix the issue, or just wait and pay for FTTP on Demand.