Need help to conver Excel to PDF 40+ files

Hi

I am creating multiple invoices for multiple client, on each month using Service invoice template which is avaiable in excel, i am creating multiple invoice using this template, each excel file for each client, when ever i am receiving request i will create a template and save into seperate folder, at end of the month i will conver everything into PDF and send it to client,

Intitally i was done this only for 10 clients, not it become 40+ so it's consuming more time for me, please help me to simplify this job, i tied with few online convetors, but it's not working properly,

Thanks!