EPOS Analysis

i Receive sales out data from retailers each week and I wish to analyse them. Looking at sales history by month, by product, or by group of products, or by group of stores. I also need tograph these out, and then produce a quick summary that I can then send to the retailers, showing them the highlights.
I also then nee a different spreadsheet that combines the above files (one for each retailer) and lets me see all the sales for the businesses together so I can analyse these and show them internally