Hi there,
Web Developer with more than 8 years of industry experience, worked with reputed clients all over the world, provided solutions for Customized applications, CMS projects, web services and many more in various business domains like e-Commerce, education, restaurant, real estates etc.
I would use "phpexcel" library to load input excel file into script and modify accordingly, lastly would save back using that library again.
Would not be a difficult task to do. Lets start this.