The payment methods for these websites are credit/debit cards or online banking. For credit card payment, ipay88 is the usual gateway used. Recently I found out that ipay88 has supported payment by AMEX card issued in Malaysia. A very good news to AMEX card holders!
For Maybank 2 card holders, you can start to charge your online purchase to AMEX to enjoy 5X treat points and additional 5% cash rebates on weekends.