Faulty 206z WiFi Router

We have had to replace two WiFi routers due to them being faulty, with one being replaced twice. Vodacom staff informed me that it is common for the 206z to give problems, and the 207 being more reliable. I have to take a router back that I received last week for freezing. The lights stay on, but the unit won't charge, reset or function at all. The previous one did the same, but also continuously rebooted. These are intermittent issues, but more faulty than not. Why can't Vodacom just exchange the 207z for the faulty 206z?<br> My wife and I use both routers for business all the time, but they are making us look bad.