There are a variety of ways to get more coins. On the Willy Wonka and the Chocolate Factory Slots page, you will see the BUY button located at the bottom left side of the page. If there is an on-going promo, you’ll see it as the SALE button. This option allows you to choose from a variety of Coin packages. When you select the package you want, you will be given payment options that Facebook provides. After completing all the necessary information and confirming your purchase, the Coins should show up in your game within a minute.
Even when you are playing, you can purchase coins while inside the room/machine. Once your game detects that you don’t have enough coins you will get a prompt to make purchase for additional coins, or if you just feel like adding more coins, you can click the Gear Icon and select Buy Credits.