Hiypic Charged Me $58 for a Premium I Never Purchased

While using the Hiypic app for free, I noticed that $58 was withdrawn from my account on Thursday, April 30, without my approval or knowledge in any way. I was only ever using the app for free, yet I was charged as if I had purchased a Premium membership. This transaction appears to have gone through Garanti Bank, from my card ending in 4660. I don't accept that such a large amount could be withdrawn through the Hiypic app without my consent and without any clear, transparent notification beforehand. I'm requesting that Hiypic fully refund the $58 that was withdrawn without authorization to my card/account, and that this transaction be canceled.