Competitive Season or Permanent bans cannot be appealed. If this is just a season ban, you will be able to resume playing Competitive next season. A player who accumulates 3 or more season bans will receive a permanent ban from Competitive Play on that account. Learn more here:
The purpose of penalizing players who are crashing or disconnecting is to encourage them to stop playing Competitive at the first sign of trouble and take time to troubleshoot the issues. If you are still finding times that you are disconnecting, please consider working on troubleshooting any potential issues by following this guide here: