I bought the second class and when I returned and check their website, you know what?
There were 35 tickets for Economy class still available. Feels dissatisfied, I called their call center and also send official complaint to KTMB President (Dr. Aminuddin) and Customer Service Response.
Official reply from KTMB president
By the end of day, they called me and told me that I can get refund for my ticket. The difference of fare is RM 7.
Metzelder says: It is advisable to fight for your rights if you are cheated or coned in any way. For public transport, you can reach out your complaints at TRANSIT or any party involved.