I'm having difficulty with the shipping classes in WooCommerce. It's a webshop containing products for mailbox and packages.
However, if the cart contains 3 or more "mailbox" products, then the shipping class should change to "package".
I've tried changing the code from this question: Change shipping class based on cart items shipping class count in Woocommerce , but I couldn't figure it out.
Can someone help me with this?