Missing airtime

So my account gets recharged with airtime on the 1st of every month. Usually my airtime lasts me until around the 25th, when I usually recharge. Today when I tried making a phone call I was told I am out of airtime, which seemed strange but I proceeded to load R110 airtime. Made one 35sec call, one 2mins 26sec and one 30 sec phone call, but according to my balance enquiry I am without airtime again. Browsing was supposed to be taken off my new data package they so eagerly sold to me. Now I am without airtime again and once again Vodacom is chowing my money.