Perhaps aneesh99 should attempt (again) to accept Anoush's original offer to send an engineer to reset the banding if the banding were limiting the speed, since it is. I think the trouble on the thread on the Plusnet forums started with that questionable statement that they would just send an engineer to reset banding if the banding were limiting the speed. I think they should have initially been advised that because the speed was within the estimate, there's nothing they're going to do about it (but obviously phrased in a nicer way). There would be no purpose to the DLM ever applying any banding in the first place if someone's just going to reset it (and there also wouldn't be any purpose in applying banding that wasn't limiting the speed). However, we were happy enough to go along with that dubious policy of sending an engineer to reset the banding, because that would achieve the desired outcome.
If the engineer visit is chargeable, I think it would be fairer for aneesh99 to pay than have the ISP (or effectively, everyone else) absorb the cost. But then I suppose it's going to be Plusnet paying for their own bad advice.