Add resume for woocoomerce downloadbe products - repost

I am using woocommerce for selling digital download products. when a customer pays for products, he gets instant download link. In woocommerce settings I put the method of download on "File Force Download" because it is more secure than direct download link. Most of my customers have low speed internet connections, and during download they face interrupted download and must download the file again from beginning. Now what I want to add resume ability for woocoomerce downloadbe products.