It’s important that you complete all the activities agreed to in the claimant commitment. If you don’t, then a sanction may be imposed. This means that you will receive less Universal Credit.
If you want to challenge the level or duration of your sanction, you can find details of how to do so on the letter telling you about the sanction. The Citizens Advice Bureau will also be able to help.
Citizens Advice - arguments for challenging a sanction
You will get a letter giving the decision about your challenge and how to take it further, if necessary.