From your tone I pick up that you don't really sound concerned by these letters, even swearing in disdain whilst signing another one.
I was concerned and furious at the start. Blatant constructive dismissal - but after chatting to a few people, they said similar things : you will leave. Only at this point when you approached CCMA/labour laywer, is the law more on your side than the the employer. Only at this stage can one present everything fairly.
Up to that point, you don't have too much of a say of what happens - BUT you need to remain calm, document every error / warning , print all the mails etc. This I have done, but have committed to leaving here and know there isn't too much I can do.
EDIT : Regarding the swearing, it was something like this :
Dolby : 'I won't sign this now'
GM : 'You have to. It's acknowledgement and says that it was explained. You can appeal later'
Dolby ' I'm pretty sure I'm within my rights to not sign'
GM 'Sign it. Appeal later'
Dolby : 'Where is this email you refer to?'
GM 'This one ... here (shows print out)
Dolby : 'That refers to another email - where is the
other email?'
GM 'I'll send after the meeting. Sign the letter and appeal later!'
Dolby 'I'm not signing'
That went on for a while. Then :
Dolby : 'ok - just give it to me' (said fsck it, under my breathe referring to the situation)