As soon as a parking company can reasonably show your actions were accepting the contract then you are in a difficult place. As you've mentioned that is a pretty well known case.
So where you have a pre-existing relationship as well as communication and/or warnings then you can't use the defence that you weren't knowingly accepting any contract.
In most cases where people receive one off tickets at a specific location (as in the OP), the reality is that they have never read any contract never mind be sued for breach of that contract.
In the OPs case, do we really think that the OP accepted a contract where they would pay £90 for going over 10 minutes of parking? Of course not, they probably didn't even know about such a charge until the letter came through the door. They can't accept a contract they know little to nothing about and contract law is written to protect against that.