Slow down.
Before you spend money on court, your first avenue is the credit card company.
Send letters to landowner and clampers demanding a refund and demonstrate why you are owed your money. Give them 14 days to respond (you may or mayt not get replies) and then send another letter giving them 7 days to refund headed '
letter before action
'.
Then contact your credit card company and send them all your paperwork and demand they refund as they are liable under the 1974 Consumer Credit Act.
They will fob you off a few times, but be persistant. They will refund eventually, but you may have to send a fair few letters. You may have to threaten THEM with
county court
, but save that for if they really do drag their heels.