Do we deserve a refund after a festival has failed?

About 15-20000 people went to a music festival in Bulgaria. During the first day of the festival the headliner (Jamiroquai) twisted his ankle and did not show up.They announced his absence at around 20:00 hour.The second day didn't even start as there were winds of up to 80-100 km/h. So now after this enormous failure, the promoters want to refund only the tickets with which people haven't entered the arena during the first day (which is insane as you could imagine how little people would have remained outside the gates after 8 pm) and refund tickets for the second day,but only if they have a bill attached to them (which in the late afternoon of the first day they were removing,knowing that people will need them for the refund). So any advice on how to proceed