I have had an ongoing issue with Plusnet and my download speed. I live about 6Km from the exchange so I am not expecting miracles but a DL speed of 300K was a bit much. After much back and forth (and to be honest the Plusnet folk were really good) I read somewhere that on a long line with it’s inherent loss, an ADSL2 connection was better than an ADSL2+.
Once I had got into the root of the router (see previous post) I forced the router to ADSL2 using the CLI and bingo my speed has settled just under 2Mb. Errors are pretty high but that is not noticeable, but the better download speed certainly is.
If you have tried everything else, try this.