Vodacom adds Data themselves them Bills me

I have 3 contract numbers with Vodacom. The 1 in question is being used by my mother. Her usual bill is roughly R280pm as its a topup contract. In the event her airtime us finished she buys her.

As I checked my statement I see her phone bill is almost R600. I phone Vodacom and they say I requested 2gb data to be added to that number in october. I did not do anything like that. Call centre attitude is like "you requested, you must pay for it"

I demand that the 2gb be cancelled immediately and without PROOF that I requested it, I demand for the invoice to be credited.

I'm sure Vodacom do **** like this to make more money off contract holders that dont spend ALLOT OF AIRTIME.

Please contact me to resolve this matter