MY Phone has been deactivated even though my account has been paid.

I have been struggling with Vodacom since November even though I have provided them with all the tax invoices of all the payments with the amounts. They have deactivated my phone. I have requested to speak to managers to no avail, and I have been passed from pillar to post. I am disgusted at there customer service department as there is no empathy or even an attempt to assist a paying customer. If I did not have a contract with them I would of found myself another service provider. After all my pleas no one is getting back to me as to why my phone was deactivated yet they continue to take my money. What happens when I stop paying them, then I will be black listed. Why do we have to deal with such poor, pathetic customer service, if it wasn't for us then they would not have a job. Don't they understand the food chain. I am asking for HELP PLEASE AS THIS IS NOT FAIR.