Scan Handler: Removing specified string from the start of a barcode

Help please!

I have a barcode that when I scan the bar code, it captures this: 2P%F%FA

I need to remove this: 2P%F%F

I need to capure it only like this ;;A

So looks like it needs to insert this ;; just before the A

Again: at the end I need to have this result  ;;A

Any help will be very appreciate.

Thanks in advance.

Manuel.