Kindly go to the official page of the examination and go to the contact us tab ,you will find a column where there will be contact email id. Drop an email to them stating your concern and also note that you should send it form the email you registered and also mention the Registration number so that it will be easy for them to track.

Which exam? There's not much we can tell you without knowing the exam you're talking about.

But in general, The best way forward is to check whether you can edit the form or not. Also, there are helplines, call on those numbers and talk to the authorities.