Email destroyed

My daughter phoned the call centre and requested a data bundle to be added to her samsung. The bundle was never added with the result that her call limit was reached and her phone soft locked. She phoned to enquire and was told that an email had been sent requesting the bundle but the bundle was never added - she was directed to credit control who saw the email and agreed that the situation needed to be corrected. On returning to the call centre however she was told that there was no longer any email ,,, I can accept that people make mistakes but to actually destroy emails and deny their existence is absolutely unprofessional in my opinion.