the last time I had this problem, i.e when I upgraded to 849NU, they changed my plan but did not change the speeds on the same day. I called up 1504 and told that CC guy that I'm on 849NU and my speed is 256kbps, whereas it shd be 2mbps. That guy understood my problem and gave me a ticket number... and it was upgraded the next day.As this thing of upgrading happens at Prabhadevi exchange, the local exchange does not have any role to play in this. Its between you and Prabhadevi Server Room guys...Just in case it does not happen thru 1504, browse other threads. Someone had once posted Prabhadevi's direct Server Room number.