Out of stock management

I have an online store and I m tiered of checking the stock of a particular stock for a site may be twice in a month .The website company wouldn’t update me with the stock .So I have to check manually all the time if the products are in stock or not .This eats up all my time .I was wondering if I could have a software to search automatically the stock of my inventory if I if the input.Like I give the product name and website it automatically finds if the product is in stock or out of stock or discontinued .I give input as a excel file with names of the product and website .The report give me a list of products which are out of stock and instock .

Can anyone help me to develop this application or website or any new concept

Thank You