Works on the site on Bitrix

1. Add to the users personal account the ability to change the payment option (a custom template is used)
2. Change the set of order statuses, set up sending notifications to the mail.
3. Add in the letter (notification of registration of goods to the mail) a link to pay for the order without authorization.
4. Set up sending notifications about changes in order statuses to the buyer via Whats up
5. Check the quantity of goods in the cart (so that it is impossible to place an order if the product has ended after it was added to the cart)
6. Add pdf invoice to the letter (the invoice is now formed after creating the order and downloaded directly to the PC).
7. Send login and password to the mail during auto-registration (when placing an order).
8. Configure the filter in the product catalog as follows (by analogy with Ya.Market, Citilink): when you select the parameter, the selected products are loaded by Ajax, when changing the parameter, without clicking the "Apply" button. While the goods are loading, the block of goods is illuminated, not active. Next to the parameter for a couple of seconds pops up the plate "Found X products" (on the mobile you need to think about how best)