VODACOM HAS TO BE THE WORST

Despite the fact that I am on a contract and carry over minutes every month, Vodacom has taken it upon themselves to charge me for calls made. I have phoned them on numerous occasions, the last times being 28 April and 05 May 2016. No one is able to assist me and they all say they are escalating my query - TO THE BACK OFFICE - WHEREVER THAT MAY BE. I need help and a refund of my money they have ******.