Thank you very much for clarifying. First of all, I am sorry to hear about the issues you have experienced in your situation. The issue is that no one can predict what your chances are of overturning the final warning because that depends entirely on the employer. You could come up with the best defence or explanation and they could still leave the current outcome in place. So you need to appreciate that all you can realistically do is appeal the decision and try your best to challenge the outcome but what happens is up to the employer and once the appeal has finished, you will not have further opportunities to challenge the employer internally.
In terms of the reasons for challenge, these will depend on whether you were given proper training about this, or if all you had to refer to was the supervisor’s actions. If appropriate training was given to you, then you should not have been copying what others were doing and should have followed your training. On the other hand, if no training was given and all you had available to refer to was what others in positions of responsibility did, then you can challenge the employer that you could not have known any better and they should be looking at disciplining those who did the wrong thing and set an example to others, rather than those who followed what they did in good faith.
If the appeal is unsuccessful, your only option is to consider whether as a result you cannot continue working there, in which case you are looking at resigning and claiming constructive dismissal in the Employment Tribunal.
Hopefully, I have answered your query in a way that is simple and easy to understand. If anything remains unclear, I will be more than happy to clarify it for you. In the meantime, thank you once again for using our services.