Additional service charge in service item

Suppose I’ve a service package for 5000 taka for 5 hours. After selling this package I’m taking advance 3000 taka from customer. For any reason 5 hours package completed in 7 hours and I will charge 2000 taka more I mean total 7000 thousand taka for extra 2 hours. How can I do that in erpnext?

You can amend the invoice and add 2 more hours or raise a new invoice for the 2 extra hours.