Your offence is being prosecuted out of time.
Section 127 of the Magistrates' Courts Act 1980 says:
Except as otherwise expressly provided by any enactment and subject to subsection (2) below, a magistrates’ court shall not try an information or hear a complaint unless the information was laid, or the complaint made, within 6 months from the time when the offence was committed, or the matter of complaint arose.
Minor offences including speeding convictions are often brought without the offenders knowledge. Debtors often first learn of it by having bailiffs turn up by surprise.
The bailiff company has taken the law into its own hands, and traced you to a new address and is trying enforcement without telling HM Court Service.
A litmus test is asking to see evidence of the Warrant of Control. If the bailiff company refuses to show it, or showed a counterfeit warrant, then they know it has the wrong address and their action is unlawful.
You revoke the proceedings and the warrant of control by making a statutory declaration and laying it before the sentencing court. Use the template below.
It is often the practice of court managers to demand you attend in person to make your statutory declaration. The law does not require a personal attendance. Their motive is to try and re-convict you there and then, and have a magistrate pass immediate sentence.
Court staff know this action is also unlawful, but try it on in a hope the defendant is less informed of Rule 37.11 of the Criminal Procedure Rules and section 14 of the Magistrates' Courts Act 1980.
Make a statutory declaration under Rule 37.11 and revoke the fine and the enforcement.
You can make a formal complaint to the court manager. When your complaint is dismissed, you can approach the Parliamentary Ombudsman.
Use this template for both complaints