Like the man says, just restart it. In my experience, BT does NOT gradually match speed to lline. I'll have a steady 1.5M for a week (+/-0.5%), then it will drop by half and sit there rock solid for a week, then halve again. Nowadays I just reset the HH. If I feel like it, I'll send BT's Bombay script jockeys a snotty eMail to vent my spleen knowing full well it won't do a scrap of good.
2Mb/s? Not in my lifetime!