Dan's right - You need to pay your original fine albeit belatedly. Doesn't really matter if you have tried to pay - this is all a result from not being paid. If the court is offering you a chance then I would take it as this is the only way you will get heard. They would be the best people to answer any questions as to financial exposure. The bailiff just needs to know that the fine is being disputed and is subject to a revised hearing that should be enough to put a hold on that. Not sure if this is a criminal case of not - if it is then you can also contact/email the local constabulary (CPO) with a plea of mitigation and if you are of good character with no history of criminal activity - suggest that prosecution is not in the public interest as this was a simple oversight - and you have paid the fine now you are finally aware of it and the court action.
Good Luck