Free Traffic Legal Advice

I’ve today also received a PCN from Excel in relation to not paying a parking charge whilst visiting their store. I genuinely had no idea that Iceland would want to charge their customers for parking and as such did not even occur to me to look for parking payment signage. Do I have any right to appeal and/or as it’s a private car park with notice of a fine from a private parking entity, should I just ignore it or shut up and pay it? Incidentally it relates to a visit from several weeks ago but only received this notice today 13/11 which is the deadline day for paying a lower charge! See dates on the attached. Any advice gratefully received

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