Airtime & data finishing my airtime

For the past week I had an issue when I topped up my airtime, after a few hours it says I don't have airtime , I topped up several time with around R150 in less that 2 days and bought data bundles still my airtime was finished. When I contacted Vodacom all they could say was that it has to be my background data usage of which I checked before and that is not the case. I am so disappointed with the network provider treats us, my airtime can be used and no one is held responsible.<br> <br> Thinking of porting