Visitor Visa - Mistake in application form

Urgent help needed please.

My in-laws have submitted their visitor visa application from Bangladesh and they have their Bio-metric appointment tomorrow with VFS. They have downloaded a copy of the application from visas-immigration.service.gov.uk site after completing the payment process and etc. However they have now found a mistake in their application. Underneath the applicants address in the application where it asks "How long have you lived in this address?" my in-laws have provided wrong information in both of their applications. They have provided their age in numbers e.g 75 instead of how long have they lived in their current address. Their bio-metric is due in less than 24 hours. Should they now cancel the application and resubmit a fresh application or should they just ignore the mistake or is there any way they can now inform someone about the mistake. In their account in visas-immigration.service.gov.uk the only option they get is to cancel the information and says that they can not change any information in their application at this stage.

Please advise urgently as they have now less than 24 hrs to action anything.

Kind regards

I think they may write/type a brief note explaining the error. When they go to the biometrics appointment, ask the VFS staff to include/upload their note with the supporting documents.