Failure to do work experience punishment

I didn’t want to do work experience because i believe it is a scam to get kids to do free work for small local businesses in the name of “experience”. Despite this, i still tried to get a placement but i received nothing back. As a result of this, my school says i will have to either work with the caretaker for the day or work in the cafeteria, i view both of these as a way of humiliation. Can i refuse to do this? What would happen if i did?