Suddenly no data available to use

Yesterday I had 700 MB left on my phone, I barely used my data, this morning when I looked my data was .0MB. That is IMPOSSIBLE!!!! I use 700 MB for almost half a month but suddenly overnight the data was used. How in the world is this possible? The funny thing is I never thought that it would happen to me. It happened to my mother in law with her ****le 2 months ago and Vodacom opened a ***** case and to date not one person from Vodacom came back to her regarding the ***** situation. I am so dissapointed that my fiance upgraded my account as the number I am using is on his name. I regret the fact that we did not change Suppliers as I know for a fact that Vodacom does not care about the fact that your data goes missing. You just have to keep on recharging and the data just keeps on dissapearing as I witnessed it with my mother in law. Not one person in Vodacom is willing to look into the fact that your data dissapeared.They all tell you the same thing,that you used it,when you know for a fact it is impossible.Please send your contact centre people on training as they all sound like parrots,not one can truly assist you.I want my data refunded as I did NOT use 700 MB overnight!!!!!