Taking data

<p>I bought 1GB data and put it on my phone which normally hold up to between 3 to 4 weeks . For the last 2 times that I put 1 GB on my phone it only lasts up to 4 hours !! I am not doing anything different than I normally do I contacted vodacom they are telling me that I did use my data and that I must make sure my settings is correct and not auto updating which I did check and is fine. When I phoned them I still had almost 200mb on my phone so I made sure everything is off on my phone and did not go on the Internet or anything and my 200mb is finish !!!!!!!!!!!!! So vodacom please explain to me where is my data !!!!!!! </p>