I won't argue this, but the T&Cs often are clearer when it's the property's choice. For example, look at the T&Cs for "standard rooms" or "standard suites" where it's explicit the property defines those. Since the T&Cs don't indicate the choice of free parking is at the property's discretion, I agree with spgplat21's interpretation and suggest ljones027 reach out to their MHC to have the charges removed.