This happened to me just last week. I received an email to say I had AUD$23.99 deducted from my iTunes balance (provided by iTunes cards purchased at 25% off so really only AUD $17.9925!) from this exact in app purchase. Needless to say I checked my account immediately and confirmed this. My credit card details were registered with iTunes but they had been mysteriously deleted. I changed my password and contacted Apple with low expectations. I was contacted by Apple within 24 hours stating that they had reversed the transaction! My account was also frozen and I had to go through a (fairly simple) reactivation process.
The email/password combo I used was my 'doesn't matter' standard generic login that I use in a lot of places (not email or banking or anywhere that matters). I thought that iTunes didn't matter as I figured the worst that could happen is someone buys me some music with my own money. I hadn't considered the dodgy app developer siphoning money through apps.
I don't see how this can't be caused by someone at Lakoo. If an in-app purchase is made from their app surely the only place the money goes is 30% Apple and 70% Lakoo. I can't understand why Apple doesn't just shut them down.
I suspect my email/password combo was harvested from some forum or similar that I innocently signed up for. The lesson here is use a unique password for iTunes.
Anyway kudos to Apple for refunding this fraudulent transaction but grrrr for not shutting this down earlier. (It's been happening for almost 6 months!)