Edited:
Just tried the chat service and asked where this particular CSO is located. In Kuala Lumpur. Not sure how trustworthy are the chat agents, on these info. I've gotten bad experience from Amazon.sg chat/call center, based in India, cannot perform a simple task and dare to argue with me against the facts (with black and white proof).
This CSO also claims all cardup is excluded. After challenging CSO with T&C, CSO came back, saying MCC 7399 is not within their "eligible list". Claims this is a "top-up". No answer when pushed with which specific clause CSO is referring to, within the terms and conditions. Or if they can send me this "eligible list", and if this list is published, vs published terms and conditions (ie, which one is more legal). Just say will refer to product manager and get back to me.
Seems like poorly trained overseas CSOs to me, just repeating some generic credit card term, instead of product specific terms. (Like SQ call center, even if overseas, I always try to get the SIN call center, I don't trust their India call center or even US-based ones). Nothing cause for concern for MCC 7399 to me, since terms and conditions have nothing against this MCC or other "top-ups" other than grab top up.