do i deserve to miss out on a day out at a top theme park ?

yesterday, i had a row with my older sister, because she is claustrophobic and hates confined spaces , i locked her in her room, i enjoyed watching her kick and screaming to be let out, i even recorded her suffering on my phone,i only meant for her to be locked in for an hour or 2, while anyway my friend rang up and i got distracted and went out, i forgot about my sister, my parents came home 8 hours later and found her locked in, she had missed her driving lesson and a date with her boyfriend, she even had to wee in a flower pot, my parents went mad and said i would be getting a taste of my own medicine , they said i will be spending ALL of this weekend which is a bank hoilday locked in my room as a punishment,as i have exams this year my parents have set me tons of school work to do , including maths , english , french and science plus 2 punishment essays, this saturday is my cousins 16th birthday and both myself and my 2 sisters are invited, its at a top theme park, my parents said i cant go as i will be locked in my room, i am going to HATE this punishment , do you think i deserve it HONEST ADVICE PLEASE ?