How can I contact Apple to get a refund?

I paid 299.000 vnd for Social good app via app store & happened error & i deducted 299.000 vnd for app store,

I have already contacted the developer ( Social goods ) but they said need directed to contact Apple directly to get back refund

Pls help me to refund for this case

Tks so much

[Edited by Moderator]