Vodacom Data

I am fuming at this moment due to the fact that over the last 5 days I bought 2500mb of data from Vodacom on my internet modem. On the 28 July I bought 1Gb data like I always do for the last year for my business emails and bank transfers (It lasts me a month). After about 40min on the internet a message came through that my bundle has been depleted. I phoned the customer care 082111 only to be told that they can do nothing about it and gave me this long speech of auto update, social media and Youtube. I then went to my Window auto update history to find that only 64mb was used for the latest update, but switched it off. I bought another 1Gb of Vodacom Data on the 31 July just to be notified again after about 40min that my data bundle has been depleted again. So I phoned customer care again to be told they are off line and cannot help me. Today I bought another 500mb because I have very important emails to send after 20min on the internet once again the message your data bundle has been depleted. Again I phoned the customer care 082111 only to be told that now my modem is faulty. I only use my laptop and internet for work and this issue is causing me to loose revenue.