I have played piano with teachers for over 10 years, but parents think I can't get a diploma by myself

It has been 5 months through this year I've been with my piano teacher and I wanted to pass my diploma without the help of my teacher for rest of the 7 months. My parents didn't give a shit I have been playing for 10 years and when I presented my idea to them they immediately started going against me and told me I needed to 'prove' to them by figuring out what was wrong with the pieces and showing up to my piano teacher already knowing what to do for a few months. AS IF 10 YEARS ISN'T ENOUGH!? Keep in mind I went to my teachers once a week and never skipped classes. My parents asked my current teacher if I could finish the diploma by myself and he called my idea ridiculous. In addition to all of this I finished my piano theory and all the grades without failing a single one. Am I in the wrong for this or is my parents tweaking out?