Leave Policy: Privilege vs. Entitlement
This is in addition to what Nathraoji has said. Please note that most companies, while designing a leave policy, include an axiomatic statement at the beginning of the policy, which is "leave is a privilege and not an entitlement." Therefore, have you checked the leave policy of your company?
Whether this statement is included or not, the procedure to avail leave is to apply for leave in advance, get it approved by the HOD, and then submit the application to HR before proceeding on leave. Sometimes situations do not leave room to follow this procedure. Therefore, companies show flexibility and allow employees to proceed on leave. Upon resumption of their duties, they can submit the application for regularization purposes. However, in such cases, before proceeding on leave, employees are expected to obtain approval from their HOD.
Did you proceed on leave without obtaining permission from your HOD? Possibly, your manager saw your lack of communication as effrontery, hence the disciplinary action.
Thanks,
Dinesh Divekar