As you say the charge occurred on private land you can appeal. Firstly you need to check if the company operating the car park is a member of a trade body, either the British Parking Association (BPA) or International Parking Community. If this is the case, you should start by appealing the charge with the company who issued the ticket first. Write to them, giving them the ticket number, your registration number, the date the ticket was issued and explain why the charge is not applicable - in this instance because the machine was faulty. Include the evidence you have of the payments that you made. You do not need to explain that you were the driver, just that you are the owner of the vehicle. Include any other evidence you have such as photographs. If this is not successful you can then appeal to the relevant trade body using the same process.

If the company is not part of a trade body, you need to write to the company in the same way and explain that because the machine was faulty and you made payments to cover the parking, you will not be paying the charge. Again, do not say that you are the driver only that you are the registered keeper, because this means you can deny responsibility for being the driver at the time and cannot be pursued for the charge. Remember to include all the available evidence you have and explain why you think the charge is unfair and will not be paid.

The crucial point to remember is that because this occurred on private land, it is not technically a parking ticket but an invoice. These companies do not have a right to fine you, only to send you an invoice based on what they see as a breach of contract. You can also complain to the owner of the land if you are not successful.