Contract Cancellation

Hello, I have 2 phone contracts with Vodacom and 1 has been depleted. I go to the store and they tell me I have to call the cancellation department and I was given the number, but the number doesn’t go through. I tried calling countless times and they ended up deducting money from my account for 2 phones instead of 1. I go back to Voda shop for the 2nd time and the same thing happens again and I’m told to call the same number that doesn’t go through. Now month end is nearing and I still haven’t cancelled my contract because they are unreachable. I don’t want a double deduction for something that has reached it expiry date. Please help me cancel my contract