Wrong National Insurance number on supporting Student Finance England application

Hello,
It's regarding my son’s student finance application. When I created my own (parent) account, I mistakenly entered my son’s National Insurance (NI) number instead of my own. As a result, he is now unable to enter his NI number on his application because it is already linked to my account.
To address this, I have uploaded my P60 along with a covering letter explaining the error. My son has also uploaded a letter from HM Revenue & Customs as evidence of his NI number.
I believe this is the correct approach, but I would like to know how long it typically takes for this kind of correction to be processed. Since his application was submitted 10 days after the 17th May deadline and includes this NI issue, I’m concerned about whether it will be resolved in time to meet the university’s deadline.
Has anyone experienced a similar issue with correcting a National Insurance number on a student finance application? If so, how long did it take for the correction to be processed?