[Issuing authority address]
[Reference: PCN number/ Date of issue]
Dear Sir/ Madam,
I am writing to formally challenge the above Penalty Charge Notice.
On [date] my vehicle [registration number] was issued with a Penalty Charge Notice for the reason of [offence code and official reason stated on PCN].
In accordance with the Traffic Management Act 2004, my challenge is on the basis that the contravention did not occur [reasons why].
Please find enclosed evidence to this effect, in the form of [give details and why it backs up your case].
For this reason, I look forward to receiving notification that the Penalty Charge Notice has been cancelled within 28 days.