1. It's treated as a civil debt
The company says you broke the car park's terms, which is a contract claim. It won't put points on your licence, but it stays on their books.
2. Debt collectors write next
Reminder letters, then debt-recovery letters, often with extra fees added on top of the charge.
3. It can end in a county court claim
The company can take you to the small claims court. If you ignore court papers, you can get a County Court Judgment (CCJ), which can hurt your credit file if it isn't paid within a month.
4. You lose your right to appeal
Appeals have deadlines. Miss the operator's window and you usually can't use POPLA or the IAS, the free independent appeal services.
The cheaper route: appeal in time if you have grounds, or pay at the early discount if you don't. Council tickets have their own rules and go up if ignored too. This is general information, not legal advice. If court papers arrive, act quickly; Citizens Advice can help for free.