After changing tariff on my payg phone with orange to the dolphin tariff I found that the sim no longer worked, typically this occurred on the day that I was sent a text confirming I was entitled to 600 free texts this month, as far as I can tell it is a sim card problem and orange have agreed to send me a new sim card, but I was wondering if this could have occurred because of a fault at Oranges end, in an attempt to encourage me to go with one of their contracts, as the phone worked perfectly fine before.

As a result of this fault I have lost all numbers that were saved to the sim but retained any that I had transfered to the phone when I first recieved it so is it possible to stop a sim from functioning server side?

Cell Phones - Nokia - 1600 Cellular Phone