Dear Vladimir
thanks for your inquiry.
Unfortunately TWINT and PostFinance Card are not supported to work in an iFrame as it is only available OffSite, which means on the Page of app-wallee.com. You will need to configure the payment method integration so it redirects to this page when the payment is confirmed. You can see how it looks here:
http://demo2.sellxed.com/woocommerce/wallee/
You can see the available supported methods per paymentmethod here:
https://app-wallee.com/processors/1470224862421/saferpay
If you have any further questions, please reply to info@customweb.com and mention the ticket number 56539 so we can help you most efficiently.
Hope I could help you.
With friendly greetings
Benjamin Stadler