Vodacom using my airtime without my permission

I am disgusted. I dont understand the point of buying data on vodacom, it used to be if your data runs out, then it stops whatever you're busy with and you will most likely get an SMS that warns you are now out of data and sometimes shows the bundle deals. Now when your data is fi ished it just freely starts using your airtime... Until there is nothing left!!!! So I can watch a video and vodacom can take ALL my data and then ALL my airtime and THEN only stops the video or whatever you are busy with and says sorry we have used everything you have now you have to load more!!!! I have airtime and I have data and it is not for you to try and finish as quickly as possible!!!! This is bull****!!! If you are going to use my airtime without my permission, at least use it to buy another bundle!