Fitnet Manager secure the validation cycle. As soon as a timesheet has been sent to validation, it's under the control of the validator.
That's why a submitted timesheet cannot be modified unless the validator cancel or return it.
The cancelled request goes back to the submitter with a Off-Workflow status. He can modify it and send it again to validation.
Status shows the state of the timesheet into the validation cycle. It can be easily spotted thanks to the color code you set up.
On each timesheet, there is a icon 
which allows employee and validator to engage in a chat. This is good opportunity for employee to ask for the return of his timesheet.