Vodacom unfair Data depletion

Good day I'm currently on a 3GB data contract,and my father is the one who is paying for the contact, my issue is that yesterday my Data just disappeared I didn't even get a notification 50%,80%and 100% that my data is about to deplet instead I got an SMS at 05:07 this morning that i have reached the national data limit and to my surprise my data connection was off through out the night,this is not acceptable and it's not the first time this has happened.the cellphone number in question is ********** 761.