IPhone 4S :: How To Stop Someone From Turning Off Their WiFi

My stepdaughter has a 5C and is constantly turning off her wifi. She says it goes off by itself, but i think she does it in case she doesn't have access to wifi and then accesses data which is driving up our phone bill like crazy. I would shut off her data but her dad is her dad and he doesn't want me to (just don't want to deal with the problems associated with that). I know that if she is in a place where she has no access to wifi, she would automatically go onto data, but i think she actually turns off her wifi too, so that she can access data. I constantly tell her she needs to leave it on, so does her dad. Is there a way to prevent someone from turning off the wifi button?

Info:
iPhone 4S, iOS 5.0.1