DLM Woes

[#1]

Since I got FTTC in August 2014, my 76/20 line has been perfect, with the ping at around 20ms. Recently, due to unknown causes, it's been downgraded to a 68 Mbps IP Profile, but I struggle to get 50 Mbps from it and upload speeds have been more than halved, which is particularly irritating. Also, ping's up to around 27-28ms. I was planning on just leaving the modem to do it's thing and slowly increase the profile again but it's actually got worse since the first decrease happened. Any ideas how to resolve it?

[#2]

There's little you can do as it will be likely down to the error rate that is causing DLM to act, short of finding out what is causing the errors ?? You could buy a modem like the billion 8800nl that allows you to access the stats  or unlock a BT or supplied Huawie HG612 modem  which may or may not give a clue as to what  has caused DLM to intervene,