There is an issue with the “My voucher” page.
If I move (front-end) in My Account –> My Vouchers (“I Miei Buoni”, in Italian) using the prestashop default theme, I get the page correctly.
If I switch to SNS Senia theme and try to get the same page, it return me a blank page.
I’ve setted a test prestashop installation, clean, there is only “SNS_Senia” Theme loaded.
Please, try to verify, try to switch theme from BO.