Now I want to know if I can go back to Ireland and appeal from there?
You were in the process of being deported from Ireland but absconded because of a lack of border controls and entered UK where you fought an ultimately fruitless battle to obtain residence in UK.
Now some time after the fact, you want to similarly exploit the porous (or nonexistent) border back to Ireland and resurrect your dead petition in a zombie like fashion?
I was refused landing in Ireland from South Africa and banned for 5
Barring a major miracle it will not be successful. Remember, per your own acknowledgement you have already been banned for five years. You have become a serial flouter of immigration laws and processes. Your plight is worse than before.
Go back to South Africa and stop wasting years on long shot immigration ventures. Unfortunately the reality is that the world and Europe is becoming more anti-immigrant, particularly anti illegal immigrant which is the category you now fall in.
Additionally stop using agents, usually thats a euphemism for conmen and human traffickers with one mission, line their own pockets at anyone’s expense.