Glastonbury fans have slammed festival organisers after they allowed 'dangerous overcrowding' during Avril Lavigne's set on Sunday. Glastonbury fans have slammed festival organisers as 70,000 people watch Avril Lavigne at 'dangerously overcrowded' stage while SZA performs to empty crowds as they argue there were MAJOR scheduling faults While hoards of festival goers rocked along to the pop punkers set, fans …