A couple of years ago, I got a PCN for not paying at all when collecting from Argos in Sainsburys there (I wrongly assumed supermarket car park would be free, genuine first-timer mistake!). I asked security in the shopping centre for someone to discuss this with and it got rescinded by speaking to whoever was senior on-site, though I can't remember their job role. Might be worth asking around during working hours! I believe they contacted the operator to get it cancelled.