There are a few reasons why you might be banned.
One possibility is that you have requested a refund for your purchases after you received the items and the refunded value exceeds $100 USD. This is an automatic ban that cannot be undone.
It's also possible that you have been banned from the game for violating the terms of service. This could be for a number of reasons, such as cheating, harassment, or spamming. As part of our role in maintaining a fair and enjoyable community, we are doing our best to make sure players adhere to our user code of conduct. This includes banning players where the developer has collected evidence of activities outlined as inappropriate within that code of conduct.
For more information, you may find the Code of Conduct under Section VIII of the Terms of Service.