I got an ‘invoice’ from Aldi’s car park police a couple of years ago. They said I’d parked there for 25 hours. An email to their chief exec’s office explaining that I had been in for less than half an hour on consecutive days and I could show them cctv pics of my car in my drive in the intervening hours, soon triggered an apology and scrubbing of the fine. So if the OP has a very good reason why he needed 11 hours in their car park, it may be worth an email, although from what he hasn’t told us, I suspect he should just pay up.