I have some problem in my card. payment is made twice

hello I have some problem in my card.
because payment is made twice.
It's not accurate, but i've heard that monthly payments have been made twice in my message
The situation appeared to have lasted about two months.

So about 20.48 dollars seems to have lasted twice and for about two months. I'm in a hurry. Tell me the answer to this.
and... I can't wait to settle this matter. I want to get a refund and use your app with confidence.

I would like to change the payment to once a month and get a refund for the payment made twice a month

Additionally...
As i am korean, it is a little hard to speak english. I hope you understand