The game cannot charge more than the amount shown in the offer. There are a few reasons why the payment in your bill does not match the offer price:
1. Taxes and fees
In some cases, your purchase may be subject to state and local taxes, depending on your location and the payment method you use. If tax is applicable, you will find the tax owed on the checkout page or in your payment confirmation.
⦁ Tax information for Google Play purchases
⦁ Apple: Payment & Pricing
⦁ PayPal: How do I view and download statements and reports?
US players: your purchase may be subject to sales taxes depending on the state’s tax laws. The amount of sales taxes will be based on your billing address or location.
A foreign national may be obligated to pay US sales taxes while being in the United States.
2. The Pay button was double-tapped
This mostly happens with mobile payments. Your payment system may withdraw the money a few times. Once your purchase is processed, Google Play or the App Store refunds the extra amount to your card. Then, our server receives a single transaction and adds the offer to your account.
3. Merged transactions (Apple)
Sometimes Apple groups your purchases together onto a single charge. Please compare your purchase history with the charges on your statement.
Here you will find an article on how App Store purchases are billed.