I Received Chat Ban and Now Want to Get Higher Mastery Levels but Can't

Hi due to my toxicness when I first started playing league again in March and April I was given a chat limiter and have improved and I try my best to keep a positive attitude and was hoping I could have my behavior bans removed so I can start getting higher mastery levels than level 5. And if there is a specific place for appeals like this could someone link me?

Thanks ~SG Naz