Got Banned on Umingle For Typing F15

I use the Umingle web version on my iPad and my account was suddenly banned after I typed “F15” as I was asked to do. Right after I entered “F15”, my account was blocked and now whenever I try to log in I only see the message “You are banned” without any explanation. I did not contact Umingle support before this, because I do not understand why such a simple action led to an immediate ban, and I believe this was either a mistake or an abuse of the system. I request that my account ban be removed immediately and my access restored, and that I be informed clearly why this ban was applied in the first place.