Poor service

I called rain about 3 days ago to tell them that my router shows an error message "insert sim or invalid sim" on the web interface and i cannot connect the internet. first i spoke to an consultant who didn't know what she was talking about, then when i spoke another consultant named Lerato she said that when there's load shedding thats what the router will display. I waited until I the towers were up again and tried to connect but I got the same error. I put the sim in another router and everything worked as it was supposed to then I called rain and explained all the steps I've taken and told them that the problem is with ZTE router they provided. these people sent an email saying my router is working just fine they can see traffic from their side. my ref number is ***