Extended Joining Date

Hi,
I require a warning letter format to send the candidate who has extended his joining date without information.
The letter should contain that the candidate has been given second chance and is supposed to report to the duty within 72hrs from the date of receipt of this letter.
Seniors please help.

Draft
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Dear Mr./ Mrs.
This is in reference to our offer letter dated........duly accepted by you and your subsequent letter dated ....for extension of joining date.
As per your request we have extended your joining date on or before ............... which is already ....days late from the original date of joining.
But we regret to note you that despite indulging you to extend your date of joining for two occasions, you have neither turned up nor shown any interest in joining with us. You are aware that extension of joining date is against company’s policies but a very special case you have been benefited.
It seems you have no interest in joining with our organization. However, as a matter of good gesture you have been given 72 hours more time to join failing which your offer of employment will be withdrawn automatically without any further correspondence in this subject.
for(Company name)

Tips for Writing a Warning Letter to Employee
This is just a short write-up of the tips or instructions for writing a warning letter to employee. These tips are not discussed in detail, and if you are from the human resources stream, you must be aware of all these things.
The following are the essentials to be mentioned in the warning letter.
Warning letter is not a joke, it actually tarnishes the work record of the employee, so before giving it, verify and then confirm the facts.
Cite the relevant policy or rule number (if any) in the beginning.
Clearly mention the employee's activity, whatever was done or is going on.
Keep the letter concise and precise.
Mention the action that would be taken, if wrong things are continued or are repeated.