magento2.3 – How to refresh summary articles in checkout

I made a module (override Discount.php in Magento_SalesRules) which adds a free product when entering a specific coupon code. So far it is working and in the summary the totals are all correct and updated.
But the view of the added product is not correct. Thubnail is not shown and the count of articles in the cart is not correct.
Have a look to the screen shot:
enter image description here
As you see, the image is not there and the total count of products in the cart still says one, not two as it should.
Does somebody have an idea how I can trigger the udate of this part of the summary?
As well, minicart is not showing the correct stuff.

Would be great if somebody does have an idea how to achieve this.
Best regards,