They would have to prove that the damage caused was done because it was unlocked.  By right if they can't they have to honour their warranty.  But like most Malaysian companies, nobody knows the law and they do what they like.  We can definitely push for it though and show it to them.

SIM card issue is an entirely hardware issue and nothing to do with bootloaders lol.  I'm not sure about local law, so I can't say much.  But overseas especially in EU and US, they have to prove that the damage was caused by unlocking, if not they have to proceed with warranty procedures.