I'll offer a slightly different perspective. All each hotel I've worked, our Sales Department always politely declined to offer discounted long-term stays. There were several reasons for this.
First, any company that provided 30-40 room nights in a year wouldn't earn any discount. Discounts are negotiated based on providing hundreds or thousands of room nights each year.
Second, a guest who stays 30-40 nights each year wouldn't even be considered one of our top guests. Essentially, that's the equivalent of 3 nights each month. We always had a handful of guests who stayed 3 nights each week.
Finally, as virtually all Sales Managers earn commissions, there's little reason to engage in negotiations over 30-40 room nights. That time is much better spent prospecting for companies that might provide 300-400 room nights.
I'm not saying that you shouldn't contact the hotel Sales Department. But, if you do and they decline, don't take it personally. It's just business. The Grand Hyatt Kuala Lumpur has 412 rooms. That's 1,470,084 room nights to fill every year. While 40 room nights is significant to you, it represents only 0.03% of their inventory.