Vodacom - Unwilling to assist

I opened a contract in 2014, after 5 years of not using the sim card, I canceled the contract and stopped the debit order. Since then, HP Attorneys have contacted me 3 times in the last year requesting that I pay the amount due.

All 3 times, I contacted Vodacom asking to cancel the contract, each time I paid the amount due. Every time Vodacom said the contract has been canceled.

Last year September I received yet another email from the attorneys claiming that I should pay this contract. Yet again I went to the Vodacom shop, paid the amount due, canceled the contract. Skip to December and I am receiving sms's from Vodacom and HP Attorneys once more.

I do not know what to do anymore? How many times should I cancel this contract? I have paid over R1500.00 for this contract and now I have to pay again. I refuse to pay and I refuse to speak to Vodacom about this for the 4th time. How do I handle this situation?