As documented in our Terms of Service, all purchases are final once made.
Please note that any independent purchase cancellation will lead to your Gems being deducted. In the case that your Gem balance becomes negative, any pending orders will be withheld and the prizes cancelled until the balance is restored to a positive value.
Please also note that cancelling the chargeback will not automatically restore your Gem balance and will need manual assistance from our support team.
As such we highly recommend contacting our support team first if any issues arise with purchases.