it was school kids!
My understanding of these new networks is that with respect to network capacity, voice calls trump data calls. So if your happily surfing the net at 3:29, come 3:30 when the school bell rings and all the kids are calling mummy or daddy to come pick them up from school, then there goes the smile off your internet surfing dial.
Has the NBN come your way yet? That would be a better choice than ADSL.