Good pay, but not flexible at all - Customer Service Assistant bei Waitrose: Mitarbeiterbewertung

I worked there whilst studying at University and was informed that there would be flexibility when it comes to exam times. I informed them of my exam dates months before and shifts I wouldn't be able to work due to the exams and many were still not give to me as days off, I even asked to be unpaid for them. This then led to me having a disciplinary as I was unable to attend a shift due to an exam.