air time and free data taken without warning

On Monday night my R50+ 50 MBS of data was taken without any warning. Called the call centre they were unapologetic basically it was my fault or my phones fault because I didn't have the free watts app tariff. I got a reference number which said my data validation record can only be shown end of next month. My need to know when did they change their tariffs & why wasn't I informed? Will I be refunded? I am very upset due this in convenience.