Mian Ji

@rynald0s That is just to add Fees, but I am looking for a solution the modify the Fees being added by another plugin.

Hi, thanks for your response.

A plugin XYZ offers custom features on base of individual product and on base of overall cart, and making this happen using Fees. I am supposed to write another plugin to modify the prices (increase/decrease) under certain conditions.
I tracked back the WooCommerce WC()->cart->add_fee() method but it looked like there is no filter hook available to modify price for a Fee.
I looked into the file \woocommerce\includes\class-wc-cart-fees.php
Your thoughts?

Thanks a lot.

This is change in core file, and not valid solution, this will be lost on plugin update, Plugin author should provide valid solution for that.