T2 Visa rejected - current visa has already expired

Hi,

I've just received a email that my application for Tier 2 visa from tier 4 has been rejected - which was applied by end of September, due to low salary amount by approximately £600. My employer has accidentally wrote the amount for last year and they are willing to match up to the current one.

The biggest issue is that my current visa has already expired on 22nd of October.

Please help, as I'm running out of time.

Thank you