Bad Services rendered

Good day , Im so unhappy with Vodacom. I had a 24 months Laptop contract with vodacom that expired in August 2015 , and after the contract expired I was told that it was upgraded with my acknowledgement and was told to do an affidavit which I did and sent to Maponya Mall branch that was sent to ***** Department and never recieved any feedback as I was the only person calling them and each time I call was told they still investigating. Now today I see that Vodacom has debited my account with the amount of R2527.71 for a contract that I do not have and never used. Have been put to ***** department to inquiry this incorrect billing because I do not owe Vodacom. Please assist urgently because now I have to suffer bank charges as my debit orders will bounce.