Reasonable punishment

My mother in law has been undermining my husbands ways of punishing my step daughter and it’s going a bit overboard. When she does bad in school he turns the restrictions on her phone on and she’s only able to use certain features. This includes no internet access. After 8:30 every night her text messaging is turned off until 7 am the next morning due to her staying up late on her phone. I think this is all very reasonable but my mother in law has started quite a bit of drama saying we treat my step daughter badly for doing these things. My question is do you ladies feel this is reasonable and justified or are we really doing something wrong here?