Look at this link
http://www.popla.org.uk/
The POPLA organisation was set up to provide a means to appeal a private parking charge. These charges are usuallyway out of proportion to the actual loss to the parking company. POPLA will set a fair amount to pay to settle the parking fee, it will normally be MUCH less than the amount asked by the parking company.
You need to appeal to Euro car parks (or any other private parking company) on the grounds that the fee asked is excessive, they will reject the appeal but they MUST give you a POPLA code. You then appeal to POPLA using the code who give you an amount to pay to settle the invoice. This is normally less than £10 often as little as £1.