No data notifications before running out

I have lost airtime purely because vodacom failed to send notification about my data running out. When data is almost finished then you should receive a notification to let you know your data is almost done, this way you can then topup again and go on. Because i got no notification i lost all my airtime!!!!! Phoned vodacom and they actually argued with me saying they do not send out these notifications! That is utter bull! They were even arrogant with me, that is including the supervisor! Vodacom is *****ing from people in south africa. How can no one see this! Useless people working there! Always just covering their own asses!