Tanya Osbourne has vowed never to let her pupils take exams set by Edexcel after she made repeated complaints about faults with the marking software - and was sent maths instead of religious studies papers to mark.
Last year, the fully-trained teacher and examiner arrived home to discover GCSE scripts had been dumped in the garden by a courier.
Ms Osbourne's complaints come a week after The TES revealed how an unqualified member of Edexcel's staff was able to mark extended writing sections of the religious studies exam after just 20 minutes' training.
Richard Pope, a desktop publisher who had not studied RE at GCSE, resigned from the board last week.
Edexcel said it was confident of its procedures, and had sent Ms Osbourne the maths papers to test if her system was working.