Plan A is always what anyone should do when they receive a PCN. In a day or so, you can log into the site to try and go through the motions of paying or appealing the PCN and it should tell you if there is any amount outstanding.
Do you have a copy of the Notice to Keeper (NtK) that you left with the store? Do you have evidence of the notes or any written confirmation from the person you dealt with tha the they were going to tell their agent to cancel the PCN?
