Bad Explanations and no warning on OOB rates

I have been a long customer of Vodacom, But after the surprise bill i received will be sure to never stick with them again. I upgraded in Dec 2015 from a topup to a smart s contract. this package came with 200mb of data. I was under the impression as with the other package you would be notified once you near your bundle data limit so that you dont have to pay fee of R2.00 per mb. To my surprise when my bill went from R765 i paid in Jan and Feb, to R7k in mar. I called the call centre to understand what was going on, but was left more confused by the first consultant who said that my contract was upgraded on the 1st of jan hence i had to pay extra but could not explain the Jan and feb bill. i then asked for a manager and that's when i spoke to Azipheli with a bad attitude, said the same that i managed my data well in feb and went wild in march hence the increase, which made no sense as my use is constant. she then took a u-turn and explained they bill a month late. also i got no warning indication that my bundle data was almost done, and i would incur OOB rate. I feel like i have been **** to , and set up by vodacom. I am not the only one who this has happened too!!!