How to prevent iPad from using Personal Hotspot?

My iPhone5 keeps advertising itself as a Personal Hotspot even though I set that to off. My WiFi only iPad keeps connecting to the iPhone HotSpot every time my WiFi router fails. This is driving up my data usage. How do I make the iPad forget the Personal Hotspot? I have already factory defaulted the Network Settings but it appears anyway. I have also changed the Personal Hotspot password on the iPhone and it connects anyway.