You've got to be careful with these, as there are conflicting accounts, and information. I am speaking from personal experience only;
I've had a few private parking notices, and threats with baliffs. I always reply asking for additional information, without accepting the ticket or fine. I never pay these fines ever, but you have to be careful. The company will take you to small claims court if you rack up enough fines with them, as it is then in their interest. The nurses is the example everyone uses, who had over 2000 worth of fines, and lost the case in court.
Yes if you've got 2k worth of fines, they're going to take you to court, and get their money. If you've got 1 or even 2, then ignore them and put them in the bin.
I had one from starbucks who said I hadn't been a patron. I asked them to prove I wasn't a patron, and they invoked the DPA saying they couldn't share that information. I explained that as they couldn't share information pertaining to me not being a patron, then I was not accepting the fine, and I wouldn't correspond with them further. They sent me another 3 notices, and then nothing.