You can't use a payment method with GrabPay if you have insufficient credits, the wrong card details were entered, the card is not supported (e.g. Prepaid cards), or if required by your bank, the OTP (one-time password) entered was incorrect.
Additionally, you will not be able to use GrabPay Credits for payment if your Credit balance is lesser than the fare before discount. With GrabPay, you can add your choice of payment method to enjoy the convenience of cashless payment. Tap your , then GrabPay and tap Add Payment Method. Supported payment methods include Visa, MasterCard and American Express.
Let us know, after checking your payment method details are accurate and supported, if you still are unable to use a payment method.