Hi Ngoc Anh Nguyen,
Perhaps you could also look for agents who specialise in properties in KL to assist you. Those registered with PropertyGuru are listed here: www.propertyguru.com.my/property-agents/kuala-lumpur
Alternatively, you may use the search bar and filter function in this website to look for units in your preferred area.
For example, properties in KLCC listed for rent below RM3,000 are here: https://www.propertyguru.com.my/property-for-rent?district_code=KL028®ion_code=MY14&area_code=KL02805&freetext=Kuala+Lumpur,+KL+City,+KLCC&listing_type=rent&market=residential&maxprice=3000&search=true
Properties along Jalan Ampang listed for rent below RM3,000 are here: https://www.propertyguru.com.my/property-for-rent?freetext=Jalan+Ampang&listing_type=rent&market=residential&maxprice=3000&area_code=KL02806&search=true
For units you're interested in, kindly contact the respective agents for more info. The agent's name, agency and contact number are located on the right-hand side of each listing's page (desktop view). You may choose to call, text (WhatsApp), or fill in your details in the form there.
Hope this helps. :)