To whom do you pay rent? You may need to ask your landlord to provide you with a copy of their lease. Once you get that, tell us what it says about parking. What it doesn't say about parking is equally important.
It would help if you showed us the PCN.
READ THIS FIRST - Private Parking Charges Forum guideYou’ve lived in the flat for five years, and that parking space is assigned to you. Even if you don’t have a written lease, your long-term use of the space and the permit system supports your right to park there. This right can override the rules of an unregulated private parking company.
The permit was inside your car as normal. It was only covered temporarily by a sunshield on the outside of the windscreen. You didn’t remove it or try to hide it, and this was clearly accidental. That’s not the same as parking without authorisation.
Even if the operator claims there was a breach of rules, it was minor and unintentional. It doesn’t justify a £100 charge, especially when you were parked in your own space anyway. That makes the charge disproportionate and unfair under consumer law.
Don’t appeal anything yet. Wait to see how many you receive. If you were parked there for three days, you might receive three PCNs. Once you know how many there are, you can deal with them together.
Take photos of the signs in your parking area. This will help show whether the signs clearly warn about displaying permits and what the charges are. It can also help prove that the operator didn’t act fairly.
Be prepared to appeal each PCN using the same explanation. You’ll appeal each one and explain that you are a resident, that the space is yours, the permit was in place but covered by a sunshield, and that this was a genuine mistake.
You should also complain to the managing agent or your landlord. Ask them to step in and tell the parking company to cancel the PCNs. As the resident, you have a valid reason to park there.