1. No such thing as inverter rosak is not fixable. Even non-inverter if major failure can throw away.
2. Gas mahal? Inverter and non-inverter can use same gas which is either R22, R410A, and R32. And R410A and R32 is more expensive than R22 because they are better, more efficient. But R22 gas will be banned in next few years because its harmful to the environment. R410A is widely used now, R32 is the future.
3. Service mahal? Why? Inverter and non-inverter only difference is extra electronic controller on the outdoor. Why the fark your serviceman charge more? Did they cleanup the electronic PCB also? I dont think so. So you kena con coz u r dumb dumb.
4. Why install mahal? Again you kena con. Installing inverter and non-inverter technically is same. Inverter might need 1 extra core wire between indoor and outdoor unit, but it is not a major problem for installation.

Be a wise consumer. Before buy research first. Almost everyone in Msia has internet access and mobile phone, can do simple google.
And if not sure don't simply spread stories that this is bad, that is bad. Its like spreading stupidness worldwide.
Yes not all service guy is honest, so you got to find legit reputable service guy.
Inverter is not even latest tech, it was invented in 80s and widely used since 90s. You dont have to be expert in AC, just read more.

If you have money any Japanese brand except Sharp (not sure how is their quality after China bought some their shares) is good to go. Panasonic, DAIKIN, Mitsubishi, Toshiba.

If tight budget, you can go for Gree or Media. These 2 are top brand in China but personally for AC I prefer Gree because they seems to focus on AC product.

And get an inverter, and try to learn how to set your AC temperature. 24 C - 25 C is the ideal comfort zone for human.