Student Finance - National Insurance Number

Hello,

I'm applying with my son (I'm his appointee) and we filled in the application online. However I've gone into the system today to see it's been approved but there's an issue with the national insurance number.

It says "You've entered a National Insurance number that matches one we already have on our system"

It says they need us to upload evidence, however when we click in that page the submit button is greyed out so we can't upload anything. I don't have his National Insurance letter to hand (would probably have to apply for another from HMRC) and I don't really want to send his original PIP award letter either.

I'm not sure what the issue can be, he's never had student finance before. He has an EHCP, and the only contact with anything to do with Student Finance was when my eldest daughter was applying and I think because my son receives PIP we had to put down how much that was if I remember correctly.

Does anyone have any ideas?

Sorry for the confusion, we've already got the number but I don't know where the original letter is so I'd have to send off for a new letter.