With a bit of luck they will accept her application. I know it's only 2 days and 1 of those days was a Bank Holiday, but they are the rules ..

If they refused her application as being invalid, then it looks like if she makes a new application with 28 days of her visa expiring then her overstaying will not affect her application. But if they do refuse her application, seek legal advice. Like I said, she might be able to get free advice from your local Law Centre,

As I said, they might tell her to apply again, thou she'll probably have to pay again. Would have to check about refunds and invalid applications.

Photocopy her application form, so that if you have to apply again, you can just copy most of the answers