Supersonic Huge Security Problem!!! Stay away!!!

I'm quite clued up when it comes to IT I worked for one of the largest IT vendors and am currently working for another large IT vendor. I decided to move my fiber connection to supersonic and worse mistake ever. They did not tell me that they want to manage my intenal network and control the router setup. They can't guarentee the network is safe what about my alarm and surveillance system. My first support call the technician said he will create a account and never came back the second said they wont support me with my own router. How can you trust a company that wants access to your private LAN. Don't use them rather go to cool ideas