Unfortunately, the only people that can get you unbanned are the admins on the wiki that blocked you. Local admins can block for whatever reason they like (including no reason). They are under no obligation to reply to your request. There is no further appeals process.
If you asked politely and non-confrontationally and they decided not to unblock you, there's nothing more you can do. Find a new wiki to spend your time on.
Make sure you look at your own actions and see whether they could have aggravated this situation. If so, make sure to try and do better in the future.