looks like you got yours about the same time as mine.
What puzzles me is that you said you changed the battery. Are you using the diamond-shaped key which uses a rechargeable battery or the square key? If you are using the diamond-shaped key, it is recharged upon slotting into the ignition. If you ae using the square-shaped key, the key might not be syncing properly with the EWS/central locking system.
For out of sync/frequency issues (if you are the ori central lock/alarm system/immobiliser system) - Go to a reputable mechanic who will help reset the key to the EWS module. While you are it, reset the whole car's ECU, EGS (gearshift) and the convenience features like your central locking (locks when the car moves, unlock driver door only or all doors, etc)
2. The central locking system is kaput but this is very unlikely.
If you are clueless, just go back to your dealership and complain. The car should still be under warranty. If they gave you more than 1 key, make sure both are sync'ed and charged.
Claim for the extra key if you only got one key. You need to go and order the key yourself but to do so, you need to lodge a police report, show the police your registration card and then order from AB/Sapura/Ingress. Key will cost about RM832(for diamond key) inclusive of taxes and shipping. Please claim from your dealer. You are entitled for a minimum of TWO keys!!!