4th BT Openreach engineer, namely, John visited July 12, 2016 Could not find any fault with my hardware - NTE5 MK3 + Hub One router but reported my throughput as attached BTW speed test carried out on August 5, 2016
Still 20Mbps throughput when assured 60+Mbps. I live 490 metres from the exchange.
Please fix slow internet speed Plusnet. This issue is now six months and four Openreach engineers unresolved.