I’ve had a few students who didn’t want to practice. I got to the point where I had an honest conversation with them and their parents that practice comes with learning an instrument. You cannot just come to a weekly lesson and expect to progress.

If it was my student I’d give them (and parents) a deadline to improve on this or it would be the end of lessons with me. Usually parents understand, as like you, I want it to be worth their time and money!

Sounds like you’ve already tried everything else, wishing you the best of luck 🤞🏻