Hi, thanks very much for your question. My name's XXXXX XXXXX I'm going to assist you with it.
This is not a parking fine despite what it may say and regardless of the manner in which it may try to imitate the kind of penalties issued by local authorities. The fact is that private companies cannot hand out parking penalties and has no right to punish you. This notice is a private land fine alleging that you breached the terms of the contract accepted by you when you parked and that they will settle for a specific amount to avoid bringing a civil claim.
Recent legislation came into force in 2012 rendering registered keeper liable for private land finds if he does not disclose the details of the driver within 28 days. This simply means that the claim can be brought against the registered keeper of the vehicle, making it easier to identify a defendant.
If you ignore this, the chances that they will actually sue are low. It does not make financial sense for them to do this in every case. If they do bring a claim, the amount of the claim can only be for the sum of the original fine and a small fee for issuing the claim (£35). They have no claim for legal or debt collection costs (despite any threats to the contrary in their letters). Also, do not be intimidated with any threats regarding damage to your credit rating (which would require a CCJ first).
To be successful in a claim they would need to show that their signage was adequate enough to create a contractually binding relationship and, crucially, they will have to prove the amount of the loss they sustained as a result of the breach. This loss will not necessarily be the same as the figure they have determined as a penalty. Their actual loss is probably only very small and, on that basis, you can consider writing to them and offering them, say £5/£10 for their administrative costs.
You may get some threatening letters (private parking companies vary in their responses) but you are only at risk of them bringing a claim in the small claims court for the original fine and the small filing fee. The amount you want to engage with them (at this stage) is up to you but, as I say, if you want to avoid the nuisance of further correspondence, you can offer a small sum by part admitting the claim.
I hope this helps. Please let me know if I can clarify anything for you.