Data blocks help you avoid your normal excess data rates, which can lead to hefty bills. 

Data blocks are turned on by default, you will be charged $10 for every 1GB (or part of) you go over your included allowance as opposed to your normal excess rates which could equate to as much as $40/1GB. You can check to see if you have data blocks turned on in My Account.  You will see a message saying 'Additional Data is $10/1GB' under the service. You can turn it off here as well but we strongly recommend leaving it turned on data blocks as it will help you avoid bill shock.