Dear K.Pongpan ka,
I am not sure if you are K.Kaew that we discussed via phone this morning. Sorry that I do not have your phone no.
From discussed with K.Sutas, MK using the payment process by Re-Direct (payment on our Payment Page). But you use API (Direct Message) for void & query transaction status only.
So, I don't think that you have to stop payment service on production. But you just test query & void transactions on UAT only ka.
Please give me your phone no. or call me to discuss in detail ka.
Best regards,