Free Traffic Legal Advice

I recently received a £60 fine for stopping in a private carpark for 4 minutes. I appealed stating that I had just pulled in to adjust my satnav whilst picking up my partner from the train station. I did not look for any signs as I was just safely pulling over for a very short time as it is proven within their fine documents. No other cat entered the carpark within the time I was stopped. They have obviously rejected my appeal but I cannot afford to pay £60 for stopping for under 5 minutes, I didn’t even get out of the car. Any advice on what to do now would be great. Thank you.