are my parents right to lock me up for stealing from a shop ?

My parents are making me spend 4 weekends locked up in my bedroom as a punishment for stealing from a shop, i am not on punishment during the week because i am at school , when i return home on friday evenings i am escorted to my room and locked in, i HATE This punishment its so so MISREABLE i have to follow VERY strict rules i have to be up at 6am then after a shower and breakfast i am locked in my room for the rest of the day, lights out and bed 9pm , my parents wont even let me wear what clothes i want i have to wear my white school shirt and black skirt, my parents said if i was in a real prison i could not wear what i want, my day is filled with nothing but boredom and confinement, i have to spend many hours at my desk doing school work including punishment essays, one on why its wrong to steal , another on unaceptable behavour and punishment and another on the purpose of punishment, i am finding my punishment hard i DONT like it ADVICE AND SYMPATHY PLEASE ?