Dear Sirs,
Nothing in your letter (wordy as it is) has any basis in Law. The terms of your service and charge as worded, applies only to those who enter in to a contract with you. Since no permit was displayed there was no agreement to the terms of your contract. Your notice is worded such that the fee only applies to those who agree to, and then breach the terms of your contract. They do not apply to those who are authorised under a different licence. Nothing in the deed between the Land owner and the leaseholder restricts who the lessee may assign a licence too. The lease clearly grants a right to use the common areas and makes no mention of you as a party.
Your terms do not apply in this instance and your claim of fees is disputed.
No doubt you will be aware of this.
best regards -
smug mode