Cell Barred because of 8ta billing wrong

I done a upgrade in December and 8ta promised me they will refund me all the money from Oct once I done an upgrade because they were billing me R349 for add on data bundle. In December they charge me R504 for add on Data bundle. I made a payment this month of R200 that is the contract that I agreed to and I feel I am not responsible for the add on data bundle. They have now suspended my cell and say they will not switch it back on before I make a R644 payment which I feel why must I pay for something I did not consent for. I want to go to the SAPS and open a docket of theft. It is ******* what they have done they must refund me. I call everyday and spend all day on the cell to be promised someone will call me back and it is nearly a week later and no one calls I ask to speak to management and still no one comes to the line or calls me back. This is ***** what 8 Ta is doing. I need help from someone Senior I am so desperate for help I want to go to the news papers what they are doing to the public. I need a response and my cell switched on today. They can listen to my calls that I made to 8ta everyday since last week.