Banding is applied by the Openreach DLM who will not remove it manually unless an Openreach engineer has found and fixed a fault. What plusnet are telling you appears to be correct.
The DLM will in time, if the line is now behaving within normal error rate paramaters, remove the banding. That can take from a few weeks to several months, from the reports of others on these forums experiencing it.
You are stuck until the auto system relents I'm afraid. The more you mess around reconnecting, if you are doing, the longer it could take.
Kindness isn't going to cure the world of all its awfulness but it's a good place to begin. Daisy Ridley.
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Edited by RobertoS (Sat 22-Oct-16 12:06:14)