You may block, unblock or even report a buyer/seller anytime inside the app.
To do this, go to their profile and tap on the 3 dots in the upper right corner and select 'Block/Unblock this Person' or 'Report'.
Additionally, you may want to leave a review about your experience - especially for repeat offenders.
To do this, open the conversation window and click Review ---> Leave Review in the top, right corner.
You may select a rating of 1-5 stars (default is 5) and leave your comments below.