I had swipe over limit for my Maybank 2 AMEX card 1 year ago and no charges imposed. You just cannot swipe. The card will be able to swipe again immediately after I made partial payment via Maybank2U so that total outstanding amount is below my credit limit.

I also called Maybank Customer Service and they informed me that no charges for over limit. But that is 1 year ago. Not sure whether is there any changes in terms and conditions now.