i think it's becoz u got diffrent port than yr previously package, and this new port on that dslam/ipdslam to that erx is congested.

there is another thing, same area, even same house, 2 phone line or more, doesnt mean all of it would go to the same dslam, if yr area is under remote dslam, then it should be the same, if yr area is linked to local exchanges dslam, since alot of dslam is there, yr line would go to any port/dslam they plug u into.