Plug in required for ecommerce site

Extra notes: Hi I have an e commerce drop ship site. I want a plug in installing to ensure automatic stock amendments This is very simple as I will stock all of merchants products so once it's in it is low maintenance plus it removes potential for painstaking alterations etc

This job was awarded once however, developer installed a free basic plug in which was not what was requested and not one that would do auto stock amendments from the dropship site to avoid daily checks and updates

Website is a wordpress site.