Poduct spreadsheet / Database

I need to check pricing on my website daily. In order to do this I must download an xml file from the site and check it against an xls spreadsheet. I do this manually and want to automatic the process. I need someone to give me the ability to read the new file each day and amend the old document - add, remove, update, amend etc. I'm happy for this to be done in either Excel or Filemaker, but I guess Filemaker would be better. I have added 2 files as an example of what I want done. The file labelled 'Daily update' has a part number, qty and cost'. I want this file to update the 'Web file to update' file with the 'part number, qty and cost'. If the product doesn't exsist, then needs to be added in the 'product number, qty and cost' in the correct columns / spots.