Do what? The DLM runs all the time automatically. Generally the only thing EE can constrain is the min NM, but I don't think they are doing so here.
You have a long line and are getting the correct speeds for it. So EE will say it is running as expected. Did EE give you a higher estimate when you signed up? It is possible they did as that BT Checker is overestimating your line.
1999: Freeserve 48K Dial-Up => 2005: Wanadoo 1 Meg BB => 2007: Orange 2 Meg BB => 2008: Orange 8 Meg LLU => 2010: Orange 16 Meg LLU => 2011: Orange 20 Meg WBC