The main difference (in this case as you are using English) is that the helpers in this forum would be unable to read the content of your images.
But with figures in your images it is reasonably easy to see the issue.
Now I don't know why this might have happened, but on the prices in the two images it would appear you have been charged for the discounted price on 3PCs for 3 years, even though the order is clearly for 3PCs for 2 years.
If you proceeded with the purchase, you can submit a Support Ticket Refund -
https://support.avast.com/support/tickets/new?form=2 Support tickets are handled on a First In First Out and can take between 5 and 10 working days, depending on payment method. Whatever you do don't submit multiple tickets as this throws you back in the line.
I don't know if it is possible to use the same form if you are just querying the incorrect price, as you wouldn't have an order ID number.
