Incorrect passing of account to legal collections

Hi took a contract with Vodacom in Nov 2014, and cancelled within the cooling of period, I received a final demand letter without being contacted once with regards to the amount they claim I owe them, once I lodged a dispute, they resolved the outstanding balance by passing a credit to bring the balance to Zero, since then I have received several calls from legal collection/attorneys claiming I still owe them the money they handed me over for, I explained to the attorneys I was listed in error, they say its not up to them to pass the account back to Vodacom, but Vodacom to recall the account, and I have been passed from pillar to post by customer care to retention to cancellation to legal and collection department asking me for information but not actually doing anything, this query is going on from 15/5 when I received the final demand letter, their service is the most pathetic and inconsistent. It doesn't look like anybody there knows what they are doing, one simple request is to recall the account from a legal status, and Lyod today wants to put me back to customer services so I can get a reference number before he assists me, my number is no longer on the network.