Data usage

I have two Vodacom 3G tablets which uses data excessively. I understand if you download then alot of data would be used but why is it while I am browsing it still uses alot of data. I've been to Vodacom Gateway 3 times to have my tablet settings changed so that it reduces data usage but that did'nt help, Every time I go into the store I am being told different things about settings. I even called the call centre which is of no use bcos you get shifted from one dept to another and no one can provide you with feedback. This is totaly frustating as I want to use the internet but I cannot due to the data usage. I was even given ref no's so that someone could call me and explain the steps but all i get is a sms which does not help. nobody returns your call. I am a new customer and must say that the service is pathetic....please could someone sort this problem...<br> <br>