Free Traffic Legal Advice

Hi, can anyone advise? I overstayed at Sainsbury’s car park where my doctors is on site. I shopped in Sainsbury's before my doctors appointment.  I ended going over the 3 hrs by 17 mins as there was an issue at my doctors and a 2hr delay. The admin team phoned me whilst i was in the car park which added to the delay. I have since changed my gp because of the issues that day. I'm really not sure if I can challenge the fine or not or how to. It's  a euro car parks parking charge. Any advice is appreciated. Thanks!