Totally incompetant Vodacom

I took out a 24 month top up contract for a wi- fi roughter, on the 23rd month i cancelled the contract so that the last installment goes through on the 24 month as agreed, on the 25' month the debit order went through again an i went to Vodashop again to cancel the contract again, this procedure was repeated until the month 28 and then i canceled the debit order with my bank, Vodacom is so incompetant that they now summons me forR1100 of which i refuse to pay because i do NOT want an upgrade or another contract, i will never take out another contract with Vodacom ever again, they are totally incompetant and they just rob me of my hard earned money, why must i pay for Vodacoms incompetance???? Sorry! I will not!