Missing Data

I have been loading 250 megs of data more than twice a day. I monitored it all. 250 megs lasted 32 minutes without me being on the internet at all. I have wifi at home and normally 250 megs would last at least a week as i do not need to use that much data in 30 minutes. I total since 13th-16 Jan, I loaded +-600 megs and all of it depleted 15-30 minutes after it being loaded on my phone. I called the call centre today and was left with and \i dont know"attitude. I can also see by the other complaints that there must be a problem within Vodacom that this is suddenly happening to their customers which needs to be investigated. I have kept all evidence of my data purchases"