That's basically correct each LLU provider has to buy GEA cable links from BT Openreach at the exchanges they wish to do so
So that it links into their LLU kit and thus avoids BTW's Network So no BT IP Profile hence a higher throughput level
Plusnet uses only BTW for back haul (no LLU) and even when there profile is set higher than BT's (78mbps) it still reduces throughput, even worse when it auto adjusts BTW IP profile 77.35 PN 77.3 or 77.2
At no point prior to buying are potential customers told about this , infact in their forums their staff even have denied it has such a noticeable effect , now that imo isn't in anyway fair to the customer , If you think about it how much bandwidth they must save by doing this,