Network too busy to make a call

Cannot make calls and calls drop for about a month. Get a "Network busy" error when dialling out. Sometimes I cannot make a call for an entire day. At times people cannot call me, all I receive is a missed call notification. I have called the customer support and they have no idea what is causing the problem. They did try to help by resetting my Network settings with me but this problem is beyond them. I have spoken to many of my colleagues who are also having difficulties with Vodacoms poor but expensive network.