How does Vodacom add another on my account without my knowledge???

I had a 36 months contract with vodacom that I was paying R384 then when term ended this year March, I didn't cancel it so that I can still receive data, in April I paid R194 so I can continue to receive data, then boom in June they deduct R1084 when I go to the store I was told that another line was added on my account, I was told to get an affidavit so they can lodge my complaint but even today they still deducted R1084, how can they deduct my money whilst they are still investigating and the money they took last month has not yet been resolved