I resigned from my previous organization with 24 hours' notice due to health issues, which prevented me from serving the notice period. I informed my previous manager, who instructed me to send a resignation email to him and CC the HR department. I followed his instructions and continued to follow up with him. However, he did not inform HR. Eventually, he advised me to contact HR directly. Now, HR claims they were unaware of my resignation, and the manager did not inform them. Despite having HR in CC, I have not received confirmation about the acceptance of my resignation. The manager initially assured me he would handle it, but now he denies any knowledge of the situation. Consequently, HR is not issuing my relieving letter. What steps can I take to resolve this issue?