Answer to your question:
1) Read the offer letter and contract of employment carefully to identify any breach in the notice period by the employee. If there is a breach, the employee must either adhere to the notice period stated in the offer letter/contract or negotiate with the employer by adjusting the balance of the notice period, possibly through utilizing accrued leaves. Persuade the employer by referencing the terms outlined in the offer letter/contract. Stay composed and avoid getting into arguments with the employer as this may exacerbate the situation. Take some time to consider potential solutions and seek assistance from professionals in the relevant field.
2) There are two options:
1) Discuss the matter with the management to resolve the issue, presenting all valid reasons why completing the full and final settlement is crucial.
2) Offer your full support in resolving the matter effectively.
3) Issues should never escalate to the point of resorting to threats. Ultimately, it is the employee who suffers the most in such situations. Employers have the necessary resources to handle various challenges. Legal action should only be considered as a last resort.