I have an Excel workbook that already contains a VBA routine for extracting rows from one or more CSV files when a Purchase Order number is entered. At the moment this macro still feels clunky: it occasionally slows down, throws vague errors, and doesn’t always guide the user if something goes wrong. All CSVs sit on the local machine, so there is no network or cloud latency to worry about—the speed gains need to come purely from smarter code. Here is what I need done: • Refactor and streamline the existing VBA so the entire process—from typing the PO to seeing the filtered results—runs in a single, fully automated click. • Repair any current bugs or crashes and tighten error-handling so problems are reported with clear, friendly messages rather than cryptic debug screens. • Insert sensible validations (e.g., blank PO, missing CSV, mismatched column headers) to prevent user mistakes before they happen. • Optimise for performance: avoid unnecessary screen refreshes, leverage efficient range handling, and release objects properly so the macro finishes noticeably faster. • Comment the code thoroughly and keep the structure tidy so a future editor can understand every major step in seconds. • Provide a concise read-me or in-sheet help tab that explains setup, common scenarios, and any new buttons or shortcuts you introduce. I will hand over the current workbook plus a sample CSV so you can see today’s flow. The final deliverable is the upgraded file, ready for everyday use, along with the annotated source and short documentation.