Telkom unauthorized deductions

Hi i have a problem with telkom i had a contract with them,when it ended they offered to give me just benefits for R99 but surprisingly at the end of the month they deducted money that we never agreed on the first month they deducted R99+R1057 end of august,then stopped using that sim contacted Telkom and they couldn't explain what happened,now they claim i owe them now its November 14 they deducted R2000 still they can clarify what is that for as i only suppose to get benefits for R99 no phones included,,Please help