Hello I am a solicitor with over 15 years experience. I will try to help you with this.
I assume that you have other access points to the car park and can move about freely within when you get there. I don't think you will have acquired a right of access through the hedge by dint of use it for a long length of time (ie through prescription).
So unfortunately the Council are able to manage their land as they wish.
Your advice that we have no right of way appears fallacious.
Can I have my money back, please?
Check my question and then check your answer.
It appears that 26 years of access through a purpose built gate does give a right of way into the car park.