Accidentally paid to remove ads. Can I undo this?

Hi.

I lifted my phone last night, clicked on the button, briefly observed the red fingerprint icon, and was then informed that payment was successful. Since the foreground mini game I was playing now no longer has adverts, I believe this is what I've inadvertently paid for.

I don't wish to pay for ads to be removed from this game. How can I backtrack please?

Part of the problem is that I never buy anything on my iPhone, and don't fully understand the mechanism by which payment was made. As such, I'm not even sure this is an iTunes Store question.

Please be aware that I feel that I've been defrauded by the software author. I find it difficult to believe that the thumbprint to make a payment was available directly after unlocking the phone, in such a way that it could be fumbled like this.

Is it possible to get a transaction history? Is there a means to recover the payment?

Thanks.