Spreadsheet Customer Data Update

I have an existing Excel workbook that holds our customer records. A fresh CSV file containing the latest information is ready, and I need the data merged into the spreadsheet once only.

Your task is to import the CSV, match it to the correct rows, and overwrite or append the following fields wherever changes are detected: customer contact details, order history, and billing information. Please preserve all formulas, sheet structure, and formatting already in place.

Deliverables
• Updated Excel file with all three information sets correctly integrated
• A short change-log (CSV or TXT) that lists any records you created, modified, or flagged as duplicates

Acceptance criteria
• No missing or duplicated records compared with the source CSV
• Consistent date, currency, and phone number formatting throughout the workbook
• File opens without errors in Excel 2016+

Accuracy and speed both matter to me; if you are comfortable working with large CSV imports, VLOOKUP/XLOOKUP, and data-cleaning functions, you’ll find this straightforward.