UPDATE - TESUP defended the claim and it went to mediation. I can't give the details but it was resolved to my satisfaction. Thanks for advice.

The big thing to me is this part... "A consideration period of at least 5 minutes (for the driver to consider whether to stay and park or to leave the Car Park without parking) will be allowed, and a grace period of at least 20 minutes will be added, to the purchased time," So, at least 5 minutes consideration and at least 20 minutes grace period, which is added to the purchased time. (Purchased time was 0:00). This gives at least 25 minutes total. No wonder the naughty PPC redacted that part of the contract!