I have been over 2gb of usage for the last 4 months and recieved txts everytime. Over 2gb this month and not recieved anything. Been reading the thread and waiting for my txt to cancel. They aint making it easy are they. How are you going about it snaps? seems i'm in the same situation as you.
BitterWallet said that I dont need a text from them to cancel, so I wrote them a letter and cancelling now! (I Hope!)