Legal Advice for freelance consultant (Kuala Lumpur)

Hi,
I am currently based in Malaysia but work with hotel companies in South East Asia.

One of my clients, located in Myanmar, hadn't paid the bill since December. After waiting for 3 weeks past payment due date and permantely following up, I informed my client I will freeze my services till the December bill is paid. The general manager of the hotel went mental and misunderstood this business decision as a thread as also the contract is finished end of this month. He doesn't listen and misunderstands every word I say or write. This all happened 10 days ago.
I want to send a final invoice in the hope they might pay which I doubt therefore I am seeking some legal advice on what are my rights as a freelance consultant. While I have a contract signed by them, I am not sure what I can do.
Did anyone have problems like that - anywhere in the world? Appreciate any advice. And if a lawyer is around here, be great to get a legal advice too. Thank you all in advanced.