Data dissapear , overcharge !

I have a 3 gig data contract for myself and one for my wife . We both have cellphone contracts with Vodacom too . I am a client since approximately 1999 / 2000 . I am being vercharged on only the data contract that i use . I pay up to 3000rand per month for the one contract . I have complained numerous times and asked for statements . Everytime I go to a shop , they say i use all my data . It is impossible , my account stands at R200 already and today is the 8th of the month . I did not change my internet usage , mainly facebook and car / bike searches on sites like carfind . How is it possible that after nearly 6years my data can be finished every month and so soon . I am not happy and will probably change to another provider as two of my contracts are due for upgrade soon .<br> <br> Louis