One possible approach is:
Meet with Dr Monsoon again and discuss all of the academic portfolio including teaching, research etc.
Explain clearly what your expectations are in terms of outputs.
Explain that you really need to see improvements and offer support in terms of mentorship and training etc.
Put meeting summaries in writing.
Your Faculty/Service HR Manager or Officer is available to support you through this process.
Dr Monsoon is very distressed with the above intervention and puts in a formal grievance under Statute VII , Part VI claiming bullying and harassment and refuses to meet with you again.
You next steps are therefore somewhat limited. You will need to refer the case to the Head of School for further consideration and action. There is nothing further you can do until the grievance has been heard and resolved.