Hip does not have a "block buyer" option. However, a Seller may refuse service in some, limited, situations.
For example, if you have experienced multiple issues with transactions when dealing with a specific buyer. In such a case, we recommend that you communicate with the buyer, and explain the situation, and ask that they withhold from making any further purchases from you. If the buyer then continues to make additional purchases from you, in most situations it would be acceptable to cancel the transaction. If the buyer has already paid, a full refund, including shipping, must be issued.
If a buyer has already made additional purchases from a Seller, before the Seller communicated their position asking the buyer to withhold future purchases, we recommend that the existing purchases be completed as-is.
Hip can review specific situations on an individual basis to provide guidance. If you need support, please contact firstname.lastname@example.org.