Update: After using Fortunica Casino a bit more, I found that their withdrawal process works differently from most online casinos.
When you request a withdrawal, they automatically split it into multiple payments of $350. For example, if you withdraw $700, it will be processed as 2 x $350 withdrawals.
The withdrawals then sit waiting for approval, which can take up to 2 days. One thing to be very careful about is that the money remains in your playing account while it's waiting for approval. This means it's still available to gamble, so you'll need to resist the temptation to play it before it's approved.
Once approved, the withdrawal moves to the next stage, where it's waiting to be sent to your bank or chosen payment method.
I initially tried withdrawing back to my bank card, but that was rejected, and I had to start the withdrawal process again using a different method.
I then chose to withdraw to my crypto account, and this worked successfully. The funds arrived in my crypto wallet without any issues.
Overall, the withdrawal process does work, but it's slower and more confusing than most online casinos. As long as you're patient and avoid gambling the pending withdrawal, you should eventually receive your money.
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