What can i do to stop a player from getting match bans?

I brought CDM but everyother game he gets a match ban, He's had over 30 yellow cards and had 5 red cards he keeps on getting match bans for stacking up high amount of yellows.

I have tried everything I could think of e.g. giving him fines putting him in the reserves but now he has match bans for the reserves.

Selling is the last thing I want to do because despite his match bans he is one of my best players.

Any advice would be welcome.