If a person is stubborn in his statement?

When we ask a person (X) to change a method that he doing something regularly. He is not ready to accept our request and he says “I will do in the same way as I did previously” whether the method he doing is right or wrong.

I need some sentences How to we explain this situation to someone else “I explained him, but he(X) is rigid in his statement (or)

He (X) he is strong in his statement (or)

He is constantly holding his statement….. He is not ready to accept our request.

I’m not fluent in English now only learning to speak. So kindly you yourself understand try to my question and give some proper sentences examples. Thanks in advance.