Was your application rejected in full or did they ask you to come on the day of the exam with signature of the witness as well ?
Because normally they would assign the date and mention WT as the code for witness signature
If you are in Delhi visit the RLO with the witness signature form all filled out and ask them if you can sit for the exam
Sometimes they might allow and you should get a new admit card there
Visiting time is
Wed : 10,30 to 12,30
Friday : 3 pm to 5 pm