Where to start with this one?
So you were ejected by a police officer, arrested then released with a caution, and no further action.
Then City's security people (which you refer to as police) now want to ban you, or is it they seeking a banning order in a court of law based on the above? They mention being drunk and public order but that's not what you were arrested for....?
Sorry but this is messed up. And if this does somehow end up in court you can expect this thread to be used in evidence, particularly the bit where you ask for help and offer to pay them whilst you're in court.
Mate, get proper legal help and delete your post.....